m 




PRACTICAL TREATISE 



ON 



HIGH PRESSURE 



STEAM BOILERS 



INCLUDING RESULTS OF 



EECENT EXPERIMENTAL TESTS OF BOILER MATERIALS, 



TOGETHER WITH 



A DESCEIPTIOW OF APPROVED SAFETY APPARATUS, STEAM PUMPS, INJECTORS AND 
ECONOMIZERS IN ACTUAL USE. 






BY / 

WILLIAM M. BARR 



'^^v..../?.6A^.../tr 

33: Of u; *..■-•>:.> 




INDIANAPOLIS, I^^OF v//^- 

YOHN BROTHER^ 
1880. 



V 



b 




'^n 



COPYRIGHT. 

WILLIAM M BAEE, 
1879. 



-^J 



&'J- 




INDIANAPOLIS: 

BAKER & RANDOLPH, 

PRINTERS. 



PREFACE. 



This book is not put forth so much as a specimen of 
book making as it is a record of notes, memoranda, experi- 
ments, practice, and experience gathered, during several 
years in which the writer has been connected in one way 
or another, with the design and manufacture of high 
pressure steam boilers. 

'No person at all acquainted with boilers would expect 
to receive at the hands of anybody an entirely original 
treatise on this subject. This book contains a considerable 
amount of practical information never before published, 
gleaned from the author's own experience, as well as val- 
uable contributions from several of his friends, who have 
had large experience in boiler making. 

The chapters on the strength of iron and steel have 
been carefully compiled from tests made with samples 
sheared from plates actually delivered for boilers under 
contract, and were not selected samples taken from the 
mill with a view to getting high results. The tables show 
that this country possesses materials for boiler construc- 
tion having qualities which are not surpassed by any iron 
or steel in any market. 

There is little doubt that the boiler of the future will 
be of steel, and considerable space has been given this 
material: many tests have been made, and records of 
the results appear, for the first time, in these pages. 

This book comes far short of being what the writer 
would like to have it, many subjects of interest to boiler 



VI PREFACE. 



makers and steam users have been omitted. Marine boilers 
have not been included, as that is a class of work whic.h is 
under a more intelligent direction than generally found in 
the smaller shops, and have less need of such data as here 
furnished ; to have included it, would have made a larger 
and more expensive book than the writer felt justified in 
undertaking. The same is also true in regard to locomo- 
tive boilers. Most of the smaller boiler shops are in 
charge of men who were once journeymen boiler makers, 
and " set up business on their own account." These per- 
sons are, as a class, good boiler makers, but having had 
little experience in estimating and designing work, other 
than the particular kind on which they have had a long 
experience, are often at a loss how to proceed ; it is pos- 
sible that this book may prove of service to many such. 

The object has not been to make this a book specially 
for boiler makers, but a hand book for engine builders, 
architects, and steam users, as well. 

The writer wishes to express his deep sense of obliga- 
tion to his many friends who have contributed and 
assisted in the preparation of much of the data which 
appears in these pages, and especially to Mr. David Greig, 
Leeds, England, Mr. George H. Atkinson, Pittsburg, 
Penn., Mr. J. M. Allen, Hartford, Conn., Mr. Coleman 
Sellers, Philadelphia, Penn., and many others. 

Free use has been made of recent papers read before 
engineering societies, and bearing on this subject; from 
which extracts have been made, and the proper credit 
given in the body of the work. 

Indianapolis, Ind., December, 1879. 



CONTENTS, 



PAGE 

I. Introduction 1 

II. Cast iron as a material for steam boilers 8 

III. Wrought iron as a material for steam boilers 15 

IV. Steel as a material for steam boilers 29 

V. Testing wrought iron or steel for boilers 66 

VI. Riveted joints '. 87 

VII. Weldingj flanging and influence of temperature..- 131 

VIII. Strength of boilers 148 

IX. Heating surface and boiler power 188 

X. Externally fired boilers 218 

XI. Internally fired boilers 257 

XII. Boiler setting 304 

XIII. Feed apparatus 337 

XIV. Heaters and economizers 374 

XV. Safety apparatus 393 

XVI. Incrustation and corrosion 422 

XVII. Sectional boilers 437 



ERRATA. 



Page 131. Eleventh line from the botton, read nearly instead of clearly. 

Page 168. See foot note, giving correct titles to tables L and LI. 

Page 171. Tenth line from top, read flues instead of tubes. 

Page 257. Last line, read originating instead of originally. 

Page 305. Engraving. The foundation at E is shown under the dimension line Y. It 

should have been placed under the center line of the front. The error is in 

the engraving only; the figures are correct. 
Page 309. Thirteenth line from bottom, read cleaning instead of clearing. 



CHAPTER I 



INTRODUCTION. 

Conditions Demanded in Boiler Construction — Materials of Construc- 
tion — Impurities Present in Crude Iron. 

How to generate steam economically is the great prob- 
lem of the steam engine of to-day. 

For many years past engineers have been devoting more 
time to the perfection of the mechanism of the engine 
than to the design and construction of the boiler and fur- 
nace. As a result, v^e have engines of superior excellence, 
supplied with boilers and furnaces faulty in design, coupled 
with an extravagant waste of fuel in service. 

In order to obtain anything like a proper economy in 
the use of fuel in generating steam, the phenomena of 
combustion must be understood to properly design and 
construct the furnace; the strength and properties of mate- 
rials to properly design the boiler. 

It is scarcely half a century since boiler pressures rarely 
exceeded ten pounds per square inch above the atmosphere. 
Gradually, however, as the superior economy and advan- 
tages of high pressure steam became more generally known, 
and the properties of the different materials of construction 
became better understood, there came also a demand for 
better boilers. This, in turn, required at the hands of the 
manufacturer greater discrimination in the selection of a 
material not only, but for improved designs and better 
workmanship. This has, in part, been accomplished, in-as- 
much as boilers are in very common use carrying a regular 

steam pressure of one hundred pounds per square inch, and 
(2) 



2 A TREATISE ON STEAM BOILERS. 

occasionally as high as one hundred and fifty pounds. 
These high pressures are the result partly of experimental 
inquiry, but are mainly due to a better understanding of 
the principles of thermodynamics, for it is in accordance 
with its teachings that these higher pressures have been 
steadily adopted, so that now there is a very general tend- 
ency, arguing from pure theory, toward extreme pressures, 
under the belief that the highest economy is to be based 
upon, and is in fact, simply a question of pressure. This 
leads us to the conditions demanded in the construction of 
a steam generator, which are. 

Safety while working under high pressures. 

Simple in construction. 

Thorough circulation of water in all parts of the boiler. 

Economical in the use of fuel. 

Durability in service. 

Facility of examination, cleaning and repairs. 

The first requisite in a boiler would seem to be that of 
safety, for without this all the other conditions are of little 
value. By safety is meant that pressure of steam which a 
boiler can generate and hold without danger of rupture. 

The safety of a boiler depends upon its form; the 
materials of which it is made; and the details of its con- 
struction. The conditions of safety and durability depend 
largely upon the selection of a suitable material — one which 
shall have considerable hardness, and at the same time, a 
high tensile strength combined w^ith a reasonable degree of 
toughness. 

Practically, the only available materials for the con- 
struction of steam generators are — cast iron, wrought iron 
and steel. Each of these have properties which are of 
value in this connection, though most of the steam boilers 
now in use are made of wrought iron. Formerly, copper 
had been used in boiler construction, especially for fire 
boxes for locomotives, and the internal heating surfaces in 



IMPURITIES IN IRON. 



marine boilers. This material has been almost entirely 
abandcned in boiler construction, notwithstanding its supe- 
rior conducting power over iron or steel ; the causes which 
have led to its abandonment are high first cost, inferiority 
in hardness and tensile strength as compared with the other 
materials named. 

The materials of construction hold such an important 
place in boiler design that some space should be given in 
a Avork of this kind to the consideration of the crude and 
finished iron employed in boiler making. Before any 
steam generator can be properly designed there must be a 
knowledge of the properties of the materials which are to 
enter into its construction; and as castings, wrought iron 
and steel, have one common starting point, it will not be 
thought out of place to give in briet outline the foreign 
elements which are contained in and which give character 
to iron and steel. The crude cast iron as it comes from the 
blast furnace, no matter what impurities it may contain, is 
known under the name of jpig iron. These are usually 
classed as either white or gray irons ; and it is probable that 
the difierence in the qualities, or properties, leading to this 
classification are due more to the infiuence of the contained 
carbon than to any other cause. The white iron approaches 
more nearly the character of an alloy than the gray iron, 
which partakes more of the nature of a mechanical mix- 
ture. The latter iron is employed for foundry use, the 
former for the manufacture of wrought iron. The prin- 
cipal impurities in pig iron are sulphur, silicon, phosphorus, 
manganese, carbon. 

Sulphur is almost always found in pig iron and has a 
remarkable infiuence on its quality. White irons appear 
to contain more of it than the gray varieties. At low heats 
it will in a measure prevent fiuidity in cast iron, causing 
it to assume a mushy appearance, which may be entirely 
overcome by the application of a higher heat, when the 



A TREATISE ON STEAM BOILERS. 



mushy appearance changes to that of a more perfect fluid. 
Sulphur diminishes the strength of castings in a very high 
degree by causing them to be cold-short, brittle and hard. 

Silicon is always present in crude as well as in refined 
irons, being next after carbon the commonest impurity met 
with in iron. When in combination with crude iron, the 
proportion is usually found to be greater in the gray than 
in the white varieties. Quantities as small as one-half of 
one per cent causes crude iron to be brittle, and its pres- 
ence in castings is regarded as injurious to quality, the best 
castings being those which contain it in the least amount. 

Phosphorus has the effect to harden cast iron, and to 
increase its fusibility. It enters into chemical union w^ith 
iron and is present in quantities rarely exceeding one to 
one and a quarter per cent in ordinary white or gray irons. 
In combination with iron it renders it close and compact, 
and has the tendency to make it cold-short when reduced 
to low temperatures or near the freezing point. Pig iron 
containing phosphorus melts easily, becomes very fluid, is 
easily managed in refining, and when contained in wrought 
iron up to a limit of one-fourth of one per cent has no 
perceptible effect on its welding power, except that it 
requires it to be done at a low heat. 

Manganese, in its chemical properties, is in many respects 
like iron, and will form similar compounds. These two 
metals have an aflinity for each other, and during the oper- 
ation of reducing the iron from the ore they enter into 
such an intimate relation as to form an alloy. Manganese 
causes iron to be more fluid when melted, and to be hard 
and brittle when cold. White iron contains more man- 
ganese than gray irons. Some ores yield an iron contain- 
ipg as much as ten and twelve per cent of manganese, 
which has the property of containing in its composition as 
much as one-twenty-fifth of its weight of carbon in a state 



IMPURITIES IN IRON. 



of chemical combination ; this iron is extensively used in 
steel making by the Bessemer process, and is generally 
known by its German name, speigel-eisen. 

Carbon is always present in pig iron. The quantity so 
found is variable, and its effect on the character of the iron 
is by no means certain. Sometimes it appears to be a 
chemical union, when it then partakes somewhat of the 
nature of an alloy. At other times it seems to have no 
affinity for the iron, and its presence in a free state in the 
pores, or rather between the crystals of the iron, is 
regarded as little else than a mechanical mixture. These 
differences are not altogether due to the quantity of carbon 
present, but rather to its state, or particular form of com- 
bination. 

Iron, when pure, is soft and malleable. Carbon adds to 
its hardness, renders it more brittle and lowers the degree 
of fusibility when a sufficient quantity of carbon is present 
to make what is known as cast iron. In this state it can 
neither be forged nor welded. 

The quantity of carbon in pig iron commonly ranges 
from one and one-half to three and one-half per cent. 

How carbon enters into combination with iron can 
hardly be said to have been satisfactorily explained. It is 
certain, however, that a small quantity of carbon has a 
very marked effect upon a large mass of iron. 

The state in which carbon is present in cast iron may 
be determined, 

1. By the appearance of the fracture. 

2. By dissolving a portion of the iron in either diluted 
sulphuric or muriatic acids. 

The former of the two is generally employed in deter- 
mining the approximate quality of pig iron and castings. 

By the latter method there is more certainty in arriving 
at the actual condition of the contained carbon. The acid 
acting upon the iron, but not upon the carbon, the latter 



6 A TKEATISB ON STEAM BOILERS. 

is left in a free state in the solution, if it so exists in the 
sample tested. After dissolving gray irons, the solution 
will contain numerous black particles, which have all the 
properties of ordinary graphite. A white iron known to 
have more carbon in its composition than the gray, when 
similarly dissolved will present fewer particles of carbon 
in the free state, because the contained carbon is in a chem- 
ical combination with the iron and is present in the solu- 
tion as a carbide ; thus presenting fewer particles of graphite 
or carbon than the former solution. 

White cast iron — So far as observed, this seems to have 
all the qualities of a perfect alloy ; that is, the mixture of 
carbon and iron produces a metal having the different 
properties from the materials which enter into its compos- 
ition.* It is harder than gray iron, or any iron in which 
the carbon is present in a state of mechanical mixture 
only. The fracture of white iron presents a surface of 
silvery whiteness, with but little luster, showing little or 
no free carbon. It is extremely hard, will resist the action 
of the file or chisel ; it is very brittle, and is unfit for any 
of the uses to which ordinary castings are applied. It 
naelts at a lower heat than gray iron, but does not become 
liquid at this low temperature, assuming, rather, a pasty 
condition, which may be overcome by the application of a 
still higher temperature. 

Mottled cast iron contains about the same quantity of 
carbon as the white and gray varieties. The condition in 
which it is held is about half combined and half in a free, 
state. It is very hard, brittle and not so elastic as gray 
iron. 

Gray cast iron is made from the pig irons in which there 
is the least carbon chemically combined, and the greater 

* Carbon being a non-metalic substance, it will be understood that the use of the word 
alloy in this sentence is unconventional, its use being applied to mixtures of metals only. 



CHILLED IRON, 



portion in the free state, as graphite. A general average 
would show about one per cent of carbon chemically 
combined and about two and one-half per cent of free 
graphite. 

Foundry pig is usually sold in the market as either 
Xos. one, two, three, ^o. 1 being the softest and ^o. 
3 the hardest. No. 1 is usually of a dark gray color, 
having large granular crystals, between which particles 
of carbon are seen and may be easily detached. In melting 
it becomes quite fluid and accurately fills the mold in 
which it is poured. It is not so hard or so strong as 
either of the other two irons named, and to make the best 
castings, portions of the "heat" should be made up of the 
lower grades, ^o. 2 pig-iron is harder and has a finer 
grain than ]^o. 1, owing to more of the carbon being in 
a combined and less in the free state. When properly 
mixed with Xo. l.it makes the best castings for machinery 
or for any use in which strength and durability are required. 
1^0. 3 iron is not in general suitable for castings which 
require working in the machine shop. It is hard, brittle 
and is saitable only for mixing with higher grades of iron 
in the production of heavy castings. 

Chilled iron is produced by a change in the condition of 
the carbon present in the cast iron from a state of mechan- 
ical mixture to that of chemical combination, brought about 
chiefiy by a sudden cooling while in a molten state. When 
pig iron is melted, or in a fiuid state, it is not improbable 
that the carbon which was present in a free state in the 
pores of the iron is dissolved and unites with the iron. 
In ordinary cooling the carbon would separate from the 
iron as in the pig iron before melting, but when the fluid 
iron is suddenly cooled the carbon is condensed by the con- 
traction of the iron and forced to remain in chemical union 
with it, instead of disengaging itself and collecting in the 
pores of the casting. 



CHAPTER II. 



CAST IRON AS A MATERIAL FOR STEAM BOILERS. 

Arguments in Favor of It — Objections to its Use — Effect of the 
Impurities found in Cast Iron — Tensile Strength of Cast Iron — 
Elastic Limit of Cast Iron — Defects in Castings — Behavior of 
Cast Iron in the Fire — On Designing Cast Iron Boilers. 

Cast iron as a material for boilers — The arguments in 
favor of cast iron as a material for steam generators and 
which must of necessity be confined to sectional boilers, 
are, 

1. That the transmission of heat thrcyagh plates of an 
equal thickness of cast or wrought iron is in favor of the 
former. 

2. That in point' of durability it excels wrought iron, 
for the following reasons : 

a. It will resist corrosion better than wrought iron. 

h. It is unaffected by the chemical impurities of 
feed water or the acids found in the pro- 
ducts of combustion. 

c. On account of its granular structure it is not 

possible for it to blister when subjected to a 
high heat in the furnace. 

d. It is not liable to be strained by inequality of 

temperature. 

3. As the parts must of necessity be small, they are 
capable of resisting very high pressures and are not 
dependent on any system of stays or braces for strength. 

4. Its low first cost, together with the certainty that 
any number of parts can be made exact duplicates of each 



OBJECTIONS TO CAST IRON. 9 

other, and the facility with which these parts can be fitted 
not only for original use but to replace defective or worn 
out sections. 

5. A defective section replaced by a new one renders 
a cast iron boiler as good as new, which is claimed as a very 
great advantage over wrought iron boilers, as a patch can 
never equal in strength the original plate. 

Objections — The objections urged against cast iron as a 
material for steam boilers are, 

1. That it is an unsuitable material, in consequence of 
its treacherous nature when subjected to high or unequal 
temperatures^ * 

2. That the cooling strains in the manufacture often 
produce flaws or other defects in the castings which are 
hidden to the eye and do not become apparent by merely 
testing them by hydraulic pressure, and which may, with- 
out a moment's w*arning, lead to a sudden and disastrous 
fracture. 

3. Cast iron seldom gives warning by any of the indi- 
cations of weakness which characterize or precede the 
failure of wrought iron. 

4. Cast iron being a crude product, there is no cer- 
tainty that castings can be made uniform in strength or in 
other qualities. 

5. Cast iron boilers are objected to on account of defi- 
cient circulation due to their construction, and especially to 
the fact that they must be made in small pieces; that 
there is difficulty in getting the steam generated into the 
steam room of the boiler, without priming; but this is a 
question of design rather than one of material — yet, as the 
material can only be used in certain sizes and forms, the 
objection is entitled to consideration. 

The arguments here presented both for and against cast 
iron as a material for steam boilers are, in the main, those 



10 A TREATISE ON STEAM BOILERS. 

offered by engineers and boiler makers when addressing 
actual or prospective purchasers. 

The reasons given for the rejection of cast iron as a 
material for steam boilers vs^ill doubtless be observed to be 
miscellaneous rather than specific. An inquiry into the 
relative properties of cast iron and wrought iron ought 
but does not show why the latter is preferred to the former 
material. Scarcely any two mines furnish iron ore of the 
same composition and it is doubtful whether any two fur- 
naces make an iron having precisely the same qualities. 
From this it will readily be understood why there may be 
some difficulty in making castings possessing certain qual- 
ities in the same degree. This latter, it may be said, is not 
absolutely essential to safety so long as the castings are 
sound and strong. 

The impurities usually found in cast iron and which 
give it character are, sulphur, which renders iron hot-shorty 
silicon or phosphorus, rendering it cold-short, and carbon, 
which gives to it its fusibility. The degree of hardness or 
softness of castings depends somewhat, but not entirely, 
upon the quantity of carbon contained in its composition. 
The carbon present in hard and brittle castings is often 
chemically combined with the iron ; while soft and tough 
castings contain perhaps the same percentage of carbon 
mechanically combined. The selection of iron for the foun- 
dry is a very important one, but can not be entered into here. 
The selection, however, must be such that castings shall 
possess moderate hardness, closeness of grain, strength and 
toughness. 

A comparison of the properties of cast and wrought 
iron will show that ordinary castings have sufficient 
strength for boilers, so that it is not on this account, but 
because of its unsatisfactory behavior in the furnace at a 
high temperature that has had most to do with its rejection. 



STRENGTH OF CAST IRON. 11 

From a mean of many experiments it may be said that 
ordinary castings have a tensile strength of about fifteen 
thousand pounds per square inch, or 6.69 gross tons. When 
special care has been exercised in the selection and mixture 
of pig iron, castings may be made of a higher tensile 
strength, and tests show that a strength of twelve to fifteen 
tons per square inch may be obtained. This, however, 
should be regarded as a maximum attainment and does not 
refer to ordinary castings, nor especially to thin cored work 
required in the sections for cast iron boilers. 

The elastic limit of cast iron varies somewhat, but is 
not far from one-third of its breaking strain. This would 
give ^ve thousand pounds per square inch as the utmost 
limit of safety in common castings. Allowing a factor of 
safety for cast iron boilers of ten, a working pressure 
would then be allowed of .223 ton or ^yq hundred pounds 
per square inch of section. This would give for sections 
three-eighths inch thick a safe working pressure of one 
hundred and eighty-eight pounds per square inch. If it 
were a question of strength merely, this would be quite 
sufficient to meet every case in ordinary practice. But 
every experienced foundryman knows that castings can 
not be relied upon with any degree of certainty. Frac- 
tures in cooling are likely to occur at any point where two 
surfaces join each other at right angles. If they differ in 
thickness, or if the two pieces are of any considerable size, 
this is almost sure to be the case. Blow holes are so 
frequentl}^ found in castings that their presence is gener- 
ally admitted in all ordinary work; as they are mostly 
below the surface there is no determining where they are 
located, to what extent they exist, or in what direction 
they lead. In addition to this, the process of cooling in 
the mold after the casting is made, introduces a class of 
abnormal strains which are brought about by the cooling 
or fixing of one portion of a casting over that of another. 



12 A TREATISE ON STEAM BOILERS. 



These strains are of a very complex character and fre- 
quently of themselves will distort if not fracture the piece 
containing them: Annealing is frequently resorted to in 
order to counteract or neutralize these strains. In large 
castings slow cooling is practised as much as possible, the 
effect of which is to develop a coarse, uneven grain, being 
finest near the surface and growing coarser and more irreg- 
ular toward the center. Where pieces join each other, 
cavities are likely to occur by reason of the irregular 
grouping of the crystals, which is one of the principal 
causes of these irregular strains. 

After a casting has been poured and consolidation 
begun, then, the more rapidly it can be safely cooled, the 
finer and more even will be the grain, and for any given 
metal the greater will be its strength. The cooling, in 
order to obtain the best results, should be uniform through- 
out the mass. To attain this, it may be necessary to 
uncover some of the thicker portions of the casting. It 
the cooling be unequal and at the same time quite rapid, 
injurious strains are brought into action which may have 
the effect, as already stated, to fracture the casting at a 
weaker point. 

The quality of cast iron may be judged somewhat by 
the appearance of the surface of fracture while still fresh. 
Soft and tough castings are coarser grained and have a 
less silvery luster than very hard castings. The judging 
of the quality of castings at sight can only be acquired by 
experience. 

Cast iron in the fire — The effects of intense heat on cast- 
ings is to melt off" all sharp projections and those parts 
necessary to the bolting of the pieces together. The m'etal 
almost invariably changes from the bright, granular appear- 
ance characteristic of good castings, to very coarse, uneven 
grains, having scarcely any metallic luster. It becomes 



THE HARRISON BOILER. 13 

extremely brittle and is so unlike its former state that it 
is utterly unfit for further use in the foundry in the pro- 
duction of castings requiring strength. 

The continued heating and reheating of any metal 
would in time destroy it, but cast iron seems to be less able 
to withstand the efi:ect8 of severe heat and repeated cooling 
than wrought iron. So far, the behavior of cast iron in 
the fire has been anything but satisfactory and at present 
it meets with but little favor among engineers as a material 
for steam boilers. That form has much to do with its 
durability and safety ought to be admitted. 

The only cast iron boiler which has had an extended 
sale in this country is that designed by the late Joseph 
Harrison, Jr., and for many years manufactured by him at 
his works in Philadelphia. Mr. Harrison was an accom- 
plished and successful engineer, who gave many years of 
valuable time in improving the details of this boiler and 
conducting experiments on a large scale, which, fortun- 
ately, his abundant means enabled him to do. It is prob- 
able that any suggestion calculated to make this boiler a 
success had at least an intelligent and impartial trial. Not- 
withstanding all this, the boiler can not be said to have 
ever become popular. 

During the autumn of 1878, a gentleman contracted, 
through the writer, for a wrought iron boiler, to replace a 
Harrison boiler, which had for thirteen years previously 
furnished the steam for driving the machinery of his mill. 
He stated that during this time the boiler worked to his 
satisfaction. 

There are other examples which go to show that when 
suitable irons are employed, and the boiler properly 
designed and cared for when in use, cast iron may be used 
in the construction of steam boilers. The essential requis- 
ites seem to be, that pieces be small and free from angular 
projections, or changes of direction if these by any means 



14 A TREATISE ON STEAM BOILERS. 

necessitate an increase of thickness at the line of juncture. 
The castings should be of uniform thickness throughout 
and contain no external bolting flanges, or other projec- 
tions, in the fire. 

Where boilers are made wholly of cast iron and subject 
to internal or bursting strains, the sections should be, pre- 
ferably, as nearly spherical as possible, and should in no 
case have flat surfaces of any considerable extent forming 
either the outside or inside of a boiler. Every section in a 
cast iron boiler must be strong enough to withstand the 
pressure of steam without any system of bracing, or stays 
of any kind, except those necessary to the bolting of the 
parts together to make a complete boiler. 

In the construction of boilers partly of wrought and 
partly of cast iron, the strains upon the latter should be. 
those of compression rather than those of extension. 



CHAPTER III 



WRuUGriT IRON AS A MATERIAL FOR STEAM BOILERS. 

Tenacity and Ductilit}^ of Iron — Properties of Iron, as Modified by 
Working — Welding — Texture of Wrought Iron — Effect of Cinder 
in Iron — Elasticity — Elastic Limit — Malleability — Flexure — 
Defects in Boiler Plates — Varieties of Plate Iron — Tests of Boiler 
Plate — Homogeneous Iron. 

Wrought iron is prepared, usually, from the harder vari- 
eties of pig iron, by a succession of processes such as refin- 
ing, boiling or puddling, squeezing, hammering, rolling, 
etc.; the primary object being to rid the iron of all the 
foreign substances contained in it which are calculated to 
reduce its strength and malleability, and, secondly, to pre- 
pare it in convenient size and shape for manufacturers' use. 

Wrought iron has for many years past been the princi- 
pal material employed in the construction of steam gener- 
ators of whatever kind. It has many qualities which make 
it a very desirable material for the purpose. That quality 
of boiler plate is judged to be the best which has the greater 
tensile strength, combined with ductility and malleability. 
These properties are affected in some measure by the 
impurities existing in the pig iron from which the plate 
iron is made, as well as the subsequent working the iron 
receives before being rolled out into plates. 

It is impossible to eliminate all the impurities in cast 
iron during its conversion into wrought iron. The follow- 
ing table gives the chemical analysis of a sample of boiler 
plate having a tensile strength of fifty-five thousand pounds 
per square inch : 



16 A TREATISE ON STEAM BOILERS. 

Iron 99.20 

Carbon 04 

Manganese. 17 

Silicon 15 

Sulphur, 03 

Phosphorus 21 

Oxygen 20 

100.00 

The above iron contained, and is included in the above 
analysis. 0.80 per cent of cinder. The noticeable thing in 
any analysis of wrought iron is the small percentage of 
contained carbon. In order to show how nearly the impur- 
ities in pig iron are removed during the process of con- 
version, the chemical analysis of an average sample of 
white iron is given below, by which a comparison is easily 
instituted: 

Iron , 89.14 

,-. , fCombined 2 45 

Carbon-^ _ -,_ 

(Free 87 

Manganese 2.71 

Silicon 1.11 

Sulphur 2.51 

Phosphorus .91 

100.00 

Wrought irons should possess in a good degree the fol- 
lowing properties : 

Tenacity, Welding power. 

Ductility, 

Each of these properties are influenced in some measure 
by the impurities in the iron, which may produce the fol- 
lowing defects : 



'O 



Cold-short iron is very brittle when cold, cracking 
badly, or breaking if bent at a sharp angle or doubled; 
but may be forged and welded at a high heat. This defect 



TENACITY OF IRON PLATES. lY 

occurs in irons which have an excess of phosphorus. Red- 
shorty or hot-short iron, may be tenacious when cold, but 
easily broken when hot; it welds with great diffi- 
culty, though tough and reliable when taken directly from 
the bar and used cold. Red shortness occurs in iron con- 
taining an excess of sulphur. 

Tenacity is that property in a material by which it 
resists a force which tends to separate or tear it asunder. 
This is a very important property in irons intended for 
steam boilers. The tensile strength of American boiler 
plate will range from forty thousand to sixty thousand 
pounds per square inch. Unless portions of the plates 
have been actually tested or the plates are known to 
have been made from blooms of the very best quality, it is 
not safe to assume a greater tensile strength than forty- 
tive thousand pounds per square inch of section. This 
applies to such irons only as are stamped by reputable 
makers as C. H. I^o. 1, and higher grades; these latter are 
usually designated by some private brand or trade mark. 
Some of these special irons are stamped and guaranteed 
sixty thousand pounds. 

Boiler plates may possess high tensile strength at the 
expense of other qualities, such as homogeneousness and 
toughness. There are manufacturers of boiler plate who 
express doubts as to whether an iron suitable for steam 
' boilers can be made having all the necessary qualities and 
at the same time possess a tensile strength greater than 
lifty-live thousand pounds per square inch. They assert 
that the iron becomes harder and more brittle as the ten- 
sile strength increases, and that the properties of hardness 
and brittleness introduced into the sheets by far outweigh 
any advantages which may be gained by the increased ten- 
sile strength. 
(8) 



18 



A TREATISE ON STEAM BOILERS. 



Toughness is an invaluable property in boiler plate., 
and means a combination of qualities, such as hardness, 
tenacity and ductility, by which the material is better ena- 
bled to withstand the effects of irregular strains, and frac- 
tures induced by concussion or bulging. 

Ductility is that property which a material possesses — 
like iron, for example — of being drawn out without break- 
ing. This elongation is produced by subjecting the iron to a 
tensile stress higher than the elastic limit when a perma- 
nent change of form takes place. It is found that tenacity 
has more influence upon the ductility of metals than mal- 
leability. We are thus led to expect that there will be 
something in common between the tensile strength and 
ductility of wrought iron. This will be affected somewhat 
by the quality of the original bar and the treatment it 
receives by subsequent working. 

The following table* shows the effect produced by dif- 
ferent modes of working, changes of temperature, etc. 
The conclusions given are founded upon a large number 
of experiments by Mr. Kirkaldy and others : 

TABLE I. 

ON THE PROPERTIES OF IRON, AS MODIFIED BY WORKING. 





TENSILK STRKNGTH. 


DUCTILITY. 


Reducing diameter by roll- 
ing 


Increased 


Reduced. 


Turning or removing the 
skin 


No alteration 


No alteration. 


Reducing diameter by forg- 
ing 

Annealing 


Increased 


Reduced. 


Reduced 


Increased. 


Welding ,. 


( Reduced from between^ 
(^ 4.1 and 43.8 per cent, j 


■ Reduced. 







=■' From "Notes on Building Construction," Rivington's London, 1879. 



TEXTURE OF WROUGHT IRON. 



19 



TABLE I — Continued. 





TENSILE STRENGTH. 


DUCTILITY. 


Stress sadiiJetilj' applied 

Additional Hammering 

Hardening in water or oil... 

Cold Toiling— plates 

Cold rolling — bars 


Reduced 18.5 per cent 

Increased 


Reduced in nearly all cases. 
Reduced. 


Increased 


Reduced. 


Doubled 


Destroyed. 

Reduced 60 per cent. 


Increased 50 per cent 

No difference 


Galvanizing 




Effect of frost, 23° F 


Reduced 2.3 per cent 

Reduced 3.6 per cent 


Reduced 8 per cent. 


Effect of frost, stress sud- 
denlY applied 


Reduced between and 30 per 
cent. 







Texture of wrought iron — Irons are usually said to be 
in texture either fibrous or granular. When wrought iron 
has been forged under a hammer directly from a bloom the 
forging presents a granular or jagged grain; this grain 
is not uniform in size in large forgings, being coarser 

the center and finest near the surface. If the 



in 



process of hammering be continued, it will become, 
when reduced to smaller bars, uniformly fine grained. 
If, however, instead of this continued hammering, the 
original forged billet be run through a train of rolls the 
texture will have changed from granular to fibrous. 
M. Janoyer in a paper on the texture of iron* main- 
tains that iron presents but a single texture, and that is 
the granular one ; all others are only metamorphoses of 
this, due to defective temperature at the moment of finish- 
ing, which does not permit Complete welding of the entire 
mass. He suggests classifying wrought iron into welded, 
non-welded and imperfectly welded irons, instead of fibrous 
and granular. When iron is pure and homogeneous its tex- 
ture is granular. The operation of puddling consists in 
stirring a mass of spongy iron in the midst of a bath of 

-'Journal Franklin Institute, vol. 68. 



20 A TREATISE ON STEAM BOILERS. 

cinder, which prevents the intimate approximation of its 
particles. This opposes a thorough welding of the mass 
and favors the production of a fibrous texture ; since dur- 
ing the subsequent working, the molecules can slide over 
each other, thus giving to the iron its fibrous appearance. 
The temperature at which iron is rolled has much to 
do with determining its texture ; for example, if two or 
more bars of crude granular iron be laid one above the 
other to form a fagot, and this fagot be raised to a welding 
heat and passed through a set of rolls, the result will be 
granular iron, if the welding temperature be maintained ; 
if, however, the temperature falls below the welding point 
the texture will then be fibrous instead of granular, because 
of the unequal temperature of the bar, which permits the 
naolecules or particles of the iron to slide over each other 
during the process of rolling. 

Cinder — All wrought irons contain more or less cinder 
in their composition, and the fibrous texture of iron may 
almost always be traced to its presence, especially when 
worked in the rolls at too low a temperature. The pres- 
ence of cinder always prevents perfect welding. Squeezing' 
the blooms as they come from the puddling furnace will 
remove a considerable portion of the cinder, but all blooms 
intended for boiler plates should be worked under a heavy 
steam hammer until all the cinder is worked out of it, if 
such a thing is possible. The presence of the cinder, oxide 
of iron, or any other substance between the surfaces of the 
two plates of iron will prevent their welding ; these foreign 
'substances between plates are the cause of blisters in boiler 
plates, by preventing perfect welding. 

Malleability is that property by which bodies may be 
drawn out by forging or hammering. Soft and fibrous 
are more malleable than hard or granular irons. 



DEFECTS IN IRON PLATES. 21 

Boiler plates seldom require reducing in thickness, or 
otherwise wrought, except at joints in which three or 
more plates intersect. Any iron at all suitable for boilers 
will possess this property in a sufficient degree. 

Flexure — A very important property in iron for boiler 
plates is that of flexure, or bending. In every act of 
bending or flanging boiler plate there are two forces to be 
overcome : 

1. The extension of the metal on the outside of the 
curve. 

2. The compression of the metal on the inside. 

As might be expected, thoroughly welded or granular 
irons bend easier than flbrous. Boiler plates which will 
stand flanging or bending to a right angle both with and 
against the grain when heated to a cherry red, and with- 
out cracking or breaking in the curve,, will be found suit- 
able for any ordinary boiler work. The lower grades of 
iron will scarcely stand such a test, except at a high heat 
and for narrow widths. 

The defects in iron boiler plates are principally imperfect 
welding, brittleness and low ductility, all of which may be 
largely overcome by a proper selection of materials in the 
earlier stages of its manufacture and by a careful manipu- 
lation during the successive operations of reheating, weld- 
ing, and especially by a thorough working under a heavy 
steam hammer. 

Ordinarily, the selection of particular brands of iron 
for the manufacture of boiler plate is entirely beyond the 
control of the persons who are to use the iron. Hence, irons 
of this class are usually guaranteed by the makers to be of a 
certain tensile strength. This is usually satisfactory to pur- 
chasers, on the general belief that if the specimen tested has 
an average tensile strength of^ say, fifty thousand pounds 
per square inch of section, it possesses the other qualities 



22 A TREATISE ON STEAM BOILERS. 

needed for a good boiler plate not requiring flanging, and 
in this manner for plates required for any service. 

Varieties of plate iron — The wrought iron plates now 
regularly offered in the market are known as either C. — 
C. 'No. 1 or C. H.— C. H. No. 1— and C. H. No. 1 flange. 

C. IRON, or charcoal iron, is the common boiled or pud- 
dled iron, rolled into bars or plates. This grade of iron is 
porous, and will become very brittle with repeated heating 
and cooling. It will not stretch much before breaking and 
will break suddenly. Its tensile strength ranges usually 
from thirty to forty thousand pounds per square inch. It 
is only suited for tank work, and ought never to enter into 
any portion of boiler construction. 

C. No. 1 IRON, or C. H. iron (charcoal hammered, as it 
is oftener known), is the same iron as the above, except 
that it is subjected to more careful working and is ham- 
mered into suitable blooms before rolling. This iron very 
much resembles the common iron in its general qualities, 
having but little elasticity and breaking with a sudden 
jerk. Like the above, it becomes very brittle by repeated 
heating and cooling, though somewhat stronger than C. 
iron ; its tensile strength ranging from thirty-five to forty- 
five thousand pounds per square inch. It is not a suitable 
iron for boiler construction. 

C. H. ]^o. 1 SHELL IRON is made from C. H. blooms, with 
the addition of selected scrap, the whole being thoroughly 
welded under a heavy steam hammer and afterward rolled 
into plates. This iron, like the two others just described, is 
injuriously affected by repeated heating and cooling, which 
has the effect to render it brittle. This is the quality of 
plate generally used in the construction of land boilers 
using pressures of steam below eighty or ninety pounds 



TENSILE STRENGTH OF IRON PLATES. 



23 



per square inch. It rarely enters into the construction of 
boilers for river or ocean service; its principal defect being 
a lack of homogeneity and imperfect welding. Its tensile 
strength is from forty to fifty thousand pounds per square 
inch. 

Shell irons are often made of a much better quality and 
higher tensile strength than the above, when ordered for 
any particular purpose. The following table gives the 
mechanical tests to which ten samples were subjected, and 
which were taken from boiler plates rolled for river steam- 
boat service ; five samples from Phillips, Nimick & Co., 
and five from Lloyd, Son & Co., both firms manufacturing 
at Pittsburg, Pa. The tests were made by Mr. G-eorge 
H. Atkinson, inspector of steam boilers at that point, the 
testing machine used being the design of Rehlie Brothers 
and of the kind furnished the United States government. 



TABLE II. 

TENSILE STRENGTH OF C. H. No. 1 BOILER PLATE. 



SAMPLE. 


BREAK- 
ING 
WEIGHT. 


TENSILE 

STRENGTH 

PER 

SQUARE 

INCH. 


ELONGA- 
TION IN 
PARTS OF 
AN INCH. 


TIME 

CONSUMED 

IN TEST, IN 

MINUTES 

AND 
SECONDS. 


WEIGHT 
ON MA- 
CHINE AT 

WHICH 
ELONGA- 
TION 
COM- 




THICK- 
NESS. 


WIDTH. 


REMARKS. 














MENCED. 




.25 


.96 


18,000 


75,000 


.125 


MIN. SEC. 
4.30 


14,500 


Stamped Phil- 


.26 


1. 00 


17,600 


67,692 


.1875 


4.00 


14,500 


lips, Nimick 
& Co., C. H. 


.25 


1.00 


17,000 


68,000 


.1875 


4.00 


14,000 


No. 1, 57.000. 


.26 


1.00 


18,600 


71,538 


.1875 


5.00 


15,000 


Short speci- 
men. 


.26 


.90 


16,800 


71,794 


.1875 


3.30 


14,000 




.24 


1.00 


14.900 


62,083 


.1875 


4.00 


13,600 


Stamped Lloyd, 


.24 


1.00 


14,700 


61,250 


.125 


4.00 


13,500 


Son & Co., 
Pittsburg, 


.24 


1.00 


13,800 


57,500 


.1875 


3.30 


12,400 


57,000. Short 


•2* 


1.00 


13,9j0 


57,916 


.T875 


4.00 


13,000 


.specimen. 


.24 


1.00 


14,200 


59,166 


.1875 


3.30 


12,500 





24 A TREATISE ON STEAM BOILERS. 



C. H. 'No. 1 FLANGE IRON is Similar to the above, the 
diflerence being that only the very best scrap iron and 
charcoal hammered blooms are used. The greatest care 
is exercised in the selection of materials, and the working 
in the forge is such as to insure thorough welding. In tex- 
ture it is less fibrous and more granular than any of the 
irons preceding it. On account of its nearer approach to 
a homogeneous structure, it is less liable to blister or crack 
in the fire. It will stand repeated heating and cooling, 
and should have good flanging qualities. The tensile 
strength should never fall below fifty thousand pounds per 
square inch, and does not often exceed sixty-five thousand 
pounds. The elastic limit will vary from eighteen thous- 
and to twenty-five thousand pounds per square inch, and 
will stretch from twenty-five to thirty per cent in ordinary 
two inch specimens. This is the highest grade of iron 
regularly offered in the market and is quite extensively 
used in the construction of marine boilers and for the 
heads and other flange plates of land boilers. 

Plates of this quality of iron are usually branded with 
the name of the maker and the guaranteed tensile strength ; 
thus: 

SMITH, JONES & CO. 
C. H. No. 1 FLANGE, 

57,000 

This method of stamping was introduced in order to 
meet the requirements of the government regulations with 
reference to the quality of plates entering into steam boil- 
ers intended for use on board steam vessels in the United 
States. The pressure of steam allowed to be carried is 
determined upon the shape pf the boiler and the tensile 
strength of the material ; hence the figures stamped upon 
the plates ought always be below the actual tensile strength 
of the plates bearing them. A sample sheared from several 
plates bearing the stamp of the makers and intended for 



SLIGO FLANGE IRON. 



25 



steamboat boiler service were taken to the Custom House, 
Pittsburg, Pa. and tested by Mr. Atkinson, with results 
as given below : 

TABLE III. 

TENSILE STRENGTH OF PHIFJJPS, NIMICK A- CO., C. H. No. 1 FLANGE IRON". 

o7,ono. 



THICK- 
NESS. 



.26 
.26 
.25 
.25 



PLK. 


BliKAK- 

ING 
WEIGHT. 


WIDTH. 


1.00 


20,600 


1.00 


16,700 


1.00 


19,:mo 


1.00 


19,900 



TENSILE 






ELONG.\- 


STRENGTH 






TION IN 








PARTS OF 


SQUARE 


AN INCH. 


INCH. 




79,230 


.1875 


64,230 


.1875 


77,200 


.1875 


79,600 


.1875 



TIME 

CONSUMED 

IN TKST, IN 

MINUTES 

AND 
SECONDS. 



MIN. SEC. 
5.00 



3.30 
4.00 
4.30 



WEIGHT 
ON THE 
MACHINE 
AT 
WHICH 
ELONGA- 
TION 
COM- 
MENCED. 



16,500 
14,500 
16,000 
16,500 



RKMARKS. 



Short specimen. 
U. 8. regulation 



The writer was shown at the works at Phillips, I^imick 
& Co., Pittsburg, Pa., another grade of flange iron named 
by them sligo c. h. no. i flange, which was guaranteed 
sixty thousand pounds tensile strength at its lowest limit- 
Specimens of both hot and cold flanging shown at their works 
attest the superior quality of this brand of iron. Its ten- 
sile strength, as given by them, w^as from sixty thousand to 
sixty-five thousand pounds per square inch, w^ith an elastic 
limit of from twenty thousand to twenty-two thousand 
pounds and a stretch of twenty-eight to thirty per cent. 
Samples of this iron, taken from plates rolled for a boiler 
intended for a western steamboat and tested by Mr. 
Atkinson, gave results as follows: 



26 



A TREATISE ON STEAM BOILERS. 



TABLE IV. 

TENSILE STRENGTH OF PLATES STAMPED, PHILLIPS, NIMICK A CO. H. 

No. 1, SLIGO, 60,000. 



SAMPLE. 


BREAK- 
ING 
WEIGHT. 


TENSILE 

STRENGTH 

PER 

SQUARE 

INCH. 


ELONGA- 
TION IN 
PARTS OP 
AN INCH. 


TIME 

CONSUMED 

IN TEST, IN- 

MINUTES 

AND 
SECONDS. 


WEIGHT 
ON THE 
MACHINE 
AT 
WHICH 
ELONGA- 
TION 
COM- 
MENCED. 




THICK- 

N ESS. 


WIDTH. 
1.00 

1.00 
1.00 

.80 
1.00 

.86 


REMARKS. 


.23 

.23 
.23 
.31 
.24 

.28 


14,800 
16,200 
15,600 
16,100 
15,700 
16,600 


64,347 
70,434 
67,826 
64,919 
65,416 
68,936 


.1875 

.1875 

.1875 

.1875 

.25 

.1875 


MIN. SEC. 
3.00 

3.30 

3.30 

4.00 

3.30 

4.00 


13,000 
14,000 
14,000 
15,400 
13,500 
14,500 


Short specimeti 
U. S. regula- 
tion. 



This firm make another and higher grade of iron which 
they call sligo special. It is a high grade of flange iron, 
specially adapted for the construction of all kinds of steam 
hoiler work. This iron will stand working into any shape 
in which it is possible to work iron, and the makers claim 
that its qualities are improved by repeated heating and 
cooling, an assertion borne out by exhibiting specimens 
which had many times been reheated and cooled and then 
doubling the plate cold. The guaranteed tensile strength 
was given at from sixty-two thousand to sixty-eight thou- 
sand pounds per square inch, with an elastic limit of 
twenty-five thousand to twenty-eight thousand pounds and 
a stretch of from thirty to thirty-three per cent. 

Another grade of iron is manufactured by them called 
SLiGO FIRE BOX IRON, having qualities the same as the pre- 
ceding iron, and a tensile strength from sixty-four thousand 
to seventy thousand pounds per square inch and elastic 
limit from twenty-eight thousand to thirty thousand 
pounds, with a stretch from thirty to thirty-three per cent. 



HOMOGENEOUS IRON. 27 



These irons are free from anything like brittleness, are 
tough and have a homogeneous granular texture, with 
occasional fibers of silky luster in bending fracture. The 
writer regrets that he w^as not able to obtain at this time 
samples from plates rolled to order, that special tests might 
be made. The figures given above are those resulting from 
tests made by the company in their laboratory upon a 
Rehlie Brothers' testing machine, for their own guidance 
in its manufacture. 

Homogeneous iron or (as it is oftener called) mild steel, 
is a somewhat recent term, used to designate a wrought 
iron of uniform granular texture throughout its mass ; it 
is not necessarily to be considered as purer than other 
wrought irons and may contain in some degree most, if 
not all, the elements usually considered as impurities in pig 
iron. The term homogeneous in this connection simply 
implies that the iron is of the same kind or of the same 
nature throughout the pjate. It should be entirely free 
from cinder, as it would be impossible to make a homogen- 
eous iron with cinder in its composition, for the reason that 
it has no affinity for and being of an entirely different 
nature from iron, will not combine with it; the presence 
of cinder in any iron prevents contact or perfect welding, 
by keeping the molecules of iron asunder and is one of 
the reasons for the fibrous character of ordinary wrought 
bar and plate irons. 

Homogeneous iron can best be made by a suitable pre- 
paration of the iron by either the Bessemer or Siemens- 
Martin process, or by melting wrought iron in crucibles 
and then casting into a solid ingot, from which the plates 
or bars may afterwards be made. 

This material is known in the market under the names 
of homogeneous iron, mild steel and hom.ogeneous steel. The 
name of ingot iron has also been proposed. The latter is, 



28 A TREATISE ON STEAM BOILERS. 



perhaps, more nearly correct than the three former and it 
is probable will come into general use in time. As iron 
does not sensibly harden unless it contains at least 0.30 per 
cent of carbon, it would appear that the use of the terrp. 
steel is scarcely allowable. At present, however, the ques- 
tion among boiler makers is, broadly, Iron vs. Steel, and in 
order to keep the two separate the term steel will be used 
in this book to designate the particular material just 
described, though homogeneous or ingot iron is, as already 
said, more nearly correct. 



CHAPTER IV. 



STEEL AS A MATERIAL FOR STEAM BOILERS. 

Faults of the Earlier Steel Plates — Qualities in Steel which Recom- 
mend it as a Material for Boilers — Its Nature must be Studied — 
— The Defects of Steel — Homogeneous Plates — Impurities which 
Affect the Quality of Plates — Tensile Strength of Steel Plates — 
Crucible Steel Plates — Bessemer Steel Plates — Open Hearth Steel 
Plates. 

Steel is usually spoken of as an intermediate metal 
between wrought and cast iron, its position being deter- 
mined by the quantity of carbon contained in its compos- 
ition. For the higher grades of steel this may be true, but 
as the quantity of carbon in steel boiler plates is often less 
than is found in samples of wrought iron, this definition, 
then, is defective. The difference between steel and 
wrought iron does not consist entirely in the quantity of 
carbon contained in the former over the latter, but rather 
that steel has been melted and cast into a malleable ingot, 
which is an entirely different thing from puddling and one 
in which the quantity of carbon contained in it has noth- 
ing to do, especially when present in very small quantities, 
as in mild or very soft steels. When there is carbon enough 
in steel to cause hardening when suddenly cooled, it then 
plays an important part in its quality and imparts to it 
properties which a,re not wanted in boiler plates, but which 
are valuable in steel intended for tools and other purposes. 

Steel is characterized by a fine granular texture, and 
when the contained carbon amounts to 0.40 to 0.50 per 
cent, it has the property of hardening and taking a tern- 



30 A TREATISE ON STEAM BOILERS. 

per. There are several varieties of steel, diflering in 
strength, hardness and ductility. The particular quality 
of steel best suited for boiler plate contains from 0.12 to 
0.20 per cent of carbon, or so little carbon as to permit a 
red heat and sudden quenching, without destroying the 
property of flexure. Ahigherpercentage of carbon increases 
the tensile strength, at a loss of ductility. 

The advantages of steel as a material for boilers were 
recognized many years ago and was so employed to a 
moderate extent. 

A leading article in Engineering, 1878, says : " It was 
not till about fifteen years ago, when plates of Bessemer 
steel were offered to the makers in quantities, that the use 
of steel for boiler making can be said to have become fairly 
established. Even up to the present day its use to any 
considerable extent for stationary boilers has been confined, 
with few and unimportant exceptions, to some half-dozen 
boiler works in the Manchester district, but these are of 
the very highest standing. Only two of these, however, 
have used steel extensively for shells, the rest having con- 
tented themselves by using it chiefly for the furnace tubes. 
Bessemer steel plates have been used for boilers of various 
kinds by upwards of fifty other makers in different parts 
of the kingdom, but as a rule against the advice of these 
makers, and (shall we say consequently?) often with unsat- 
isfactory results." "For marine boilers, steel plates have 
been used only to a very limited extent. Of forty of the 
best known firms of marine engine builders, including 
those who make for the Admiralty, up to a very recent 
date only about half a dozen had used steel plates and 
half of these would not have used them if they had had 
their own way." 

The steel furnished in this country, as well as that made 
abroad during most of this time, not possessing the proper- 
ties required to make its employment a success, fell into dis- 



WORKING STEEL PLATES. 31 

favor and has been for along time under a cloud; many man- 
ufacturing establishments well known to the writer declin- 
ing to have anything to do with it — others employed it 
because contracts called for it, but with the understanding 
there should be no recourse for damage in case of failure. 
No doubt this has had much to do with the little attention 
given to the production of a reliable steel boiler plate. At 
this time, however, a marked change is observed in manu- 
facturers and users alike. There is a growing demand for 
steel boilers, not only in this country, but in Europe. From 
the present outlook it seems almost certain that the boiler 
of the future will be of steel. 

Steel as a material for steam boilers recommends itself 
on account of its homogeneity, tensile strength, malleabil- 
ity, ductility, freedom from laminations and blisters. It 
requires greater care in working than is usually given to 
iron. It is a higher material and requires a higher intel- 
ligence to properly work it. This intelligence means a 
knowledge of the properties and peculiarities of the mate- 
rial. Steel differs so much from wrought iron that in 
order to work it properly its nature must be studied 
and understood. To demand that it shall conform to 
all the ordinary practice of working w^rought iron is 
absurd. If it can do so, well ; if not, then the method 
of working must conform to the nature of the mate- 
rial. Steel is not a nriaterial of definite quality and its 
properties vary w^ith each change of quality. It can be 
made almost as hard as a diamond, certainly hard enough 
to cut glass. There is no substance known which equals 
in elasticity a good steel watch spring. It is possessed of 
a toughness which is unapproached by any other kind of 
metal ; it has strength in all directions and before it breaks 
it will yield even to fifty per cent. It njay be hardened, 
tempered or annealed at will. During these processes the 
material is studied and is worked in such manner as is best 



82 A TREATISE ON STEAM BOILERS. 

suited to its quality. IS^o one thinks of subjecting bar iron 
and bar steel to the same Ireatment in the forge or work- 
shop. It is not unlikely that many failures in steel boiler 
plates have arisen from the want of this very precaution 
at the outset. A steel plate was used just as an iron plate^ 
and because it failed under such treatment the material 
was condemned as untrustworthy and dangerous — a sweep- 
ing verdict, which can come only of impatience, careless- 
ness or ignorance. 

There is no doubt that many of the earlier faults in 
steel were due to imperfections in manufacture or impru- 
dent handling and cooling after rolling. But now that 
plates are carefully made and annea^led after shearing to 
dimensions, the burden of the responsibility rests largely 
upon the boiler maker. 

Quoting again from Engineering the writer sums up 
his review of steel for boilers as follows: 

" That of some eighty boiler makers who have fairly 
tried steel plates, only some eight or nine can be said to 
have persevered with its use and used it extensively; that 
where the use of steel plates has been persevered in against 
the advice and feeling of the boiler maker, the result has 
generally been unsatisfactory ; that it may be taken for 
granted that the prejudice on the part of boiler makers 
against the use of steel is, as a rule, inversely proportion- 
ate to the extent of their acquaintance with it. It would 
appear that those makers who have not been alive to the 
difference required in the working and treatment of iron 
and steel, or who have gone timidly to work and let the 
workman find out for themselves the best way to treat 
steel, have usually had trouble and have only been too 
glad to receive a confirmation of their adverse opinion." 

The defects in boiler 'plates — For steel, the principle 
defects are brittleness, low ductility, and flaws induced by 



DUCTILITY IN STEEL PLATES. 33 

the presence of cavities formed by bubbles of air or gas in the 
original ingot. The two former may partially be overcome 
by a still further removal of the foreign substances which 
aflect the softness of steel and by reducing it to a more 
nearly pure iron. The latter is not so easily overcome ; it 
is doubtful whether a cavity once formed by a bubble of 
air or gas in the body of an ingot can ever be welded by 
subsequent hammering or working of any sort, owing to 
the interior surface of the cavity being lined with a film 
of oxide which may be brought into close surface contact, 
but not welded. Such a cavity, flattened down during the 
process of hammering and rolling into a mere surface con- 
tact, must be regarded as an incipient fracture, which may 
at any time spread to almost any extent and in any direc- 
tion, when the conditions are such as to induce it. The 
harder the steel the greater the certainty of such exten- 
sion of fracture; this tendency is diminished as softness 
and ductility are increased. 

In steel plates ductility is a property of very great 
importance, for without it plates are liable to give way 
without any of the usual indications of failure or even a 
moment's warning. Other things being equal, ductility 
increases in this material as its tensile strength is dimin- 
ished. It is only in homogeneous irons or mild steels, as 
they are usually called, which' possess this property in the 
highest degree, and these are not usually made having a 
tensile strength higher than about seventy thousand 
pounds per square inch; a reduction to sixty thousand 
or even fifty-five thousand pounds will be found to be still 
more ductile. Some experiments by Mr. Charles Huston 
on American steels exhibited the following results: 
(4) 



34 



A TREATISE ON STEAM BOILERS. 



TABLE V. 





TENSILE 
STRENGTH. 


CONTRACTIOK OF 
AREA, PER CENT. 


Crucible steel (not quite hard enough to temper) 

Crucible steel (ordinarily soft) 


78,3G6 
64,0(10 
54,600 


26.66 
36.83 


Siemens-Martin steel (exceptionally soft) 


47. 







The increase in ductility, in proportion to the decrease 
in tensile strength, is quite marked. 

There is a limit to the amount of ductility which can 
be given homogeneous plates, arising from the practical 
difficulty in the manufacture of solid ingots. This diffi- 
culty is not entirely confined to mild steels, though the 
ingots are apt to be more spongy in a soft and ductile 
metal than in the harder varieties. 

This fact has engaged the attention of steel makers for 
some years and plans for compressing the fluid steel have 
been suggested by several prominent manufacturers, among 
whom are Sir Henr^^ Bessemer and Sir Joseph Whitworth. 
The latter subjects the molten steel to a pressure of some 
six tons per square inch, by which all cavities are closed 
up, the gases contained in them driven out, the metal being 
compressed to about seven-eighths of its original bulk, its 
density and strength being greatly increased. Owing to 
the groat cost of compressing steel by either of the above 
methods, it can not be at present adopted in the commer- 
cial production of boiler plate. 

The writer saw at tbe Edgar Thompson steel works, 
w4iat is now their regular practice, the compression of steel 
ingots by steam. After pouring the ingot a cap is placed 
over the top of the mould and securely fastened by a key, 
making a steam tight joint. A flexible tube leads from 
this cap to a conveniently arranged steam pipe. A pressure 
of about seventy-five pounds of steam is used in compress- 



HOMOGENEOUS STEEL PLATES. 35 

ing the fluid ingot, and has given very satisfactory results. 
The absence of anything calculated to impair the quality 
of the ingot is a valuable feature in the process. 

Homogeneous steel plates are expected to possess in a 
good degree, tenacity and ductility, and to be more nearly 
equal in these properties when tested both lengthwise and 
across the grain than is usual in fibrous wrought iron plates. 

In Mr. Kirkaldy's tests of Krupp's and Yorkshire iron 
plates, the differences in tensile strength were found to be 
as follows: 

LENGTHWISE OF THE GRAIN. 

Krupp — Stress per square inch of fractured 

area 85,144 lbs. 

Yorkshire — Stress per square inch of fractured 

area 61,140 lbs. 

ACROSS THB GRAIN. 

Krupp — Stresss per square inch of fractured 

area 65,359 lbs. 

Yorkshire — Stress per square inch of fractured 

area 54,110 lbs. 

These specimens were nnannealed. The figures show 
an average of nine specimens of Krupp's iron and an 
average of eighteen of the Yorkshire iron. 

It will be observed that in Krupp's iron the difference in 
tensile strength, when taken in the two directions, stands 
85,144 to 65,359, or the iron is 30.3 per cent stronger in 
the direction of the fiber than across it. And similarly 
the Yorkshire iron has an increased strength of thirteen 
per cent in the direction of the fiber over that taken from 
across the plate. 

Mr. Kirkaldy made some tests of the Landore-Siemens 
steel for the English Admiralty in 1875, in which it was 
shown to be a remarkably homogeneous metal, with results 
as follows : Unannealed plates, 0.37 inch thick, 10 inches 
between supports, ultimate strength per square inch length- 



36 A TREATISE ON STEAM BOILERS. 

— , • 

wise of grain, 72,878 pounds; ultimate strength per square 
inch across the grain, 72,670 pounds; or a difference of 
only .00286 per cent, showing it to be much superior in 
this particular property than either of the two former irons. 

A homogeneous steel plate will be a doubtful gain if 
secured at the expense of even a partial loss of ductility 
over the very best iron plates now manufactured. 

One of the principal faults of a homogeneous plate is its 
liability to fracture from very slight surface or edge imper- 
fections when under high tension — imperfections which 
would scarcely, if ever, affect a fibrous iron plate. In 
such a case the stronger steel plate would obviously be 
inferior to an iron plate, not in strength, but in trust- 
worthiness. A fracture once begun in a homogeneous 
plate will extend from the edge into the body of the plate 
if that be the direction of least resistance. In this respect 
it is almost the very opposite of iron, which usually con- 
fines its fractures to the line of rivet holes, or if in the 
body of the plate the fracture usually follows the direction 
of the fiber slowly and does not extend in the rapid man- 
ner in which it is apt to do in a steel plate. 

So far as correcting mere fractures in a plate are con- 
cerned much can be said in favor of a fibrous over a homo- 
geneous material. It is not an uncommon practice where 
fractures are discovered in iron plates to stop its extension 
by simply drilling a hole at the end of the fracture and 
inserting a rivet — the fractures often being repaired 
without removing the plate. 

There is little doubt that a homogeneous plate will 
resist strains which induce fracture much longer than iron 
plates of the same thickness, but once the fracture is 
started a homogeneous plate will allow its extension in a 
shorter time and to a greater extent than a tough fibrous 
plate would. Still, with all its drawbacks, a good tough 



IMPURITIES IN STEEL. 37 



homogeDeous metal of reasonable tensile strength and 
high ductility is, all things considered, the best material 
that can be selected for boiler construction. 

The ordinary impurities which affect the quality of 
steel are phosphorus, sulphur and silicon. 

Phosphorus renders steel cold-short, and as boiler plates 
are usually worked cold, the less there is of it in the plates 
the better. The highest allowable limit in good steel 
boiler plate is 0.08 per cent and should not exceed 0.05 or 
0.06 per cent if possible; it having no perceptible effect 
on plates at that percentage. 

Sulphur renders steel hot-short and thus affects the 
working in the steel works rather than in the boiler shop, 
except in flange plates. Sulphur should not exceed 0.05 
per cent in steel boiler plates and even at this percentage 
the plates should contain at least 0.25 of manganese in 
order to counteract the hot- short effects of the sulphur. 

Silicon in steel boiler plate, even in small quantities, 
renders it hard and decreases its ductility. It ought not 
to exceed 0.05 per cent in any steel intended for steam 
boilers. 

Copper is sometimes found in steel and when present 
in any appreciable quantity renders steel hot-short and 
has a marked effect upon its welding properties when 
present in quantities exceeding 0.03 to 0.05 per cent. 

The effect of carbon in steel is to increase its hardness 
and to decrease its fusibility and welding power. 

The following table shows the effect of different quan- 
tities of carbon in steel and iron : 



38 



A TREATISE ON STEAM BOILERS. 



TABLE Vr. 

SHOWING THE CHARACTERISTICS OF IRON AND STEEL FOR DIFFERENT 

PROPORTIONS OF CONTAINED CARBON. 

{Bauermann's Metallurgy). 



NAME. 


PERCENTAGE 
OF CARBON. 


PROPERTIES. 


1. 

2. 
3 


Malleable iron-" 

Steely iron 

Steel 


0.25 
0.35 
0.50 
1.00 to \M 
1.75 
1.80 
1.90 
2.00 
6.00 


Is not sensibly hardened by sudden cooling. 
Can be slightly hardened by quenching. 
Gives sparks with a flint, when hardened. 
Limits of steel of maximum hardness and teuacitv 


4 


Steel 


5 


Steel 


Superior limit of welding steel. 

Very hard cast steel, forging with great difficulty. 

Not malleable hot. 


fi 


Steel 


7 


Steel 


8 


Cast iron 


Lower limits of cast iron, can not be hammered. 


9 


Cast iron 


Highest carbureted compound obtainable. 







The percentage of carbon in the above table is greatly 
in excess of that used in the manufacture of boiler plate ; 
the quantities in actual use for this grade of metal may be 
found in the analyses of the different samples of steel as 
given in this chapter. 

Tensile strength of steel boiler steel — This is a subject on 
which opinions have, in the past, widely differed. There 
is little doubt that the earlier steel boiler plates were made 
of too high tensile strength and too little ductility. At 
present most English engineers require that the plates 
shall in no case exceed twenty-nine tons (64,960 lbs.) per 
square inch. It is found, however, that steel with 
a strength of twenty-six tons (58,240 lbs.) per square 
inch will weld better and with more certainty than 
steel of a higher strength. A mild steel is more eas- 
ily worked and less likely to be injured by careless hand- 
ling than steel of high grade, and if it can be kept as low 

'"Wrought iron, not malleable cast iron. 



REQUIREMENTS OF LLOYD's REGISTER. 39 

as sixty thousand pounds tensile strength per square inch, 
preserving ductility and toughness, it will be amply strong 
and will meet every ordinary requirement in boiler con- 
struction. 

Requirements of steel plates entering into the construc- 
tion of steam boilers made under the supervision of Lloyd's 
Register of British and Foreign Shipping : 

1. "The material to have an ultimate tensile strength 
of not less than twenty-six tons (58,240 lbs.) and not more 
than thirty tons (67,200 Hbs.) per square inch of section, 

2. "A strip cut from every plate used in the construc- 
tion of the furnaces and combustion chambers and strips 
cut from other plates taken indiscriminately, heated uni- 
formly to a low cherry red heat and quenched in water of 
82° Fahrenheit, must stand bending to a curve of which 
the inner radius is not greater than one and a half times 
the thickness of the plates tested. 

3. "All the holes to be drilled, or if they be punched 
the plates to be afterwards annealed. 

4. "All plates, except those that are in compression, 
that are dished or flanged, or in any way worked in the 
fire, to be annealed after the operations are completed. 

5. "The boilers upon completion to be tested in the 
presence of one of the society's engineer surveyors, to not 
less than twice the intended working pressure." 

The three competing steels now in this market are cru- 
cible steel, Bessemer steel and the Siemens-Martin steel. 
The latter is oftener known as Open Hearth steel. 

These are to be regarded as distinguishing processes 
rather than three different kinds of steel, as they do not 
necessarily produce a material having chemical or mechan- 
ical properties widely differing from one another. 

Crucible steel boiler plate — The practice of Park, Brother 
<fc Co., Pittsburg, Pennsylvania, in the manufacture of cru- 



40 



A TREATISE ON STEAM BOILERS. 



cible steel boiler plate, is to select a suitable wrought iron, 
one which shall be as low in carbon and as free from 
impurities as possible. These bars are cut up into short 
pieces and are afterwards packed in crucibles containing a 
charge of about eighty pounds each. These crucibles also 
.contain a very small quantity of charcoal, just enough to 
render the iron fluid, so that it may be poured from the 
crucible into an ingot mould. These ingots are then rolled 
into plates. 

The testing of the plates in the mill consists in shear- 
ing ofl* a strip an inch or more in width, heating it to red- 
ness and plunging it into water, allowing it to remain 
there until cold; the sample is then bent over double and 
hammered down with a sledge or steam hammer, until the 
surfaces touch, as shown in the engraving, figure I. 




Figure I. 



If the steel will stand this test without showing any 
signs of fracture it "passes inspection" and is then sheared 
to the sizes required for the market. Should the sample 
show a fracture or crack in bending, the whole plate is 
rejected as being unfit for steam boilers. 

A difficulty in the manufacture of crucible steel plate 
is to keep down its tensile strength. This requires great 
care in its manufacture, for if the tensile strength is too 
low the plates are apt to be soft or spongy in some places 
and harder in others; this, of course, would not be a 
homogeneous material and would, in consequence, be unfit 
for boiler making. 

The lowest practical limit of crucible cast steel boiler 
plate is about sixty thousand pounds tensile strength ; the 
maximum tensile strength should not greatly exceed 



CRUCIBLE STEEL PLATE. 41 

eeventy-five thousand pounds. Crucible steel ranging in 
tensile strength from sixty-five thousand to seventy 
thousand pounds and having ductility enough to elongate 
eighteen to twenty per cent on a two inch specimen, has 
been found to be a good steel in practice. Park, Brother 
& Cc. have succeeded in making a sixty thousand T. S. 
steel which elongated thirty per cent in a two inch speci- 
men. The amount of carbon in the sample tested was 
0.16 per cent; another sample containing 0.27 per cent of 
carbon elongated twenty-five per cent in a two inch speci- 
men and stood a tensile strength of seventy-five thousand 
pounds. 

The quality of crucible steel boiler plate depends 
more upon the quantity of carbon contained in its compo- 
sition than upon any other element. The following 
analj^sis by Park, Brother & Co. shows the composition of 
their standard seventy thousand pound boiler plate: 

Carbon (combined) 0. 301 

Carbon (graphite) none 

Silicon 0492 

Phosphorus •. 0.0298 

Sulphur 0.0163 

Manganese 0.0643 

Iron (by difference) 99.5394 

100.0000 

The following analysis of the same grade of metal from 
the same firm, was made at the Midvale Steel Works, 
Kicetown, Pa , by K. Kent and H. G. DeBrunner : 

AVERAGE OF SIX ANALYSIS. 
Park, Brother & Co., Homogeneous Boiler Plate, Seventy Thousand Pounds. 

Carbon (combined) 0, 28 

Carbon (graphite) none 

Silicon 0.05 

Phosphorus 0.03 



42 



A TREATISE ON STEAM BOILERS. 



Sulphur 0.02 

Manganese 0.10 

Iron (by difference) 99.52 

100.00 

Analysis of Park, Brother & Co., homogeneous boiler 
plate, seventy thousand pounds tensile strength, as deter- 
mined at the School of Mines, Stockholm, Sweden: 

Carbon 0.290 

Silicon 0.040 

Phosphorus 0.033 

Sulphur 0.015 

Manganese 0.050 

.428 
[Iron, by difference 99.572] 

100.000 

The mechanical tests given below are by Mr. Atkinson : 

TABLE Vir. 

TENSILE STRENGTH OF PARK, BROTHER & CO. HOMOGENEOUS (CRUCIBLE) 
BOILER PLATE, 70,000 POUNDS. 















WEIGHT 




SAMPLE. 


BREAK- 
ING 
WEIGHT. 


TKNsrr.E 

STRENGTH 

PER 

.SQUARE 

INCH. 


ELONGA- 
TION IN 
PARTS OK 
AN INCH. 


TIME 

CONSUMED 

IN TEST, IN 

MINUTES 

AND 
SECONDS. 


ON THE 
MACHINE 
AT 
WHICH 
ELONGA- 
TION 
COM- 




THICK- 
NESS. 


WIDTH. 


KEMARKS. 










-- ■ 




MENCED. 












MIN. SEC. 






.27 


.98 


20,000 


75,.585 


.25 


5.00 


14,500 


Short specimen 


.27 


.98 


19,700 


74,452 


.25 


5.00 


15,000 


U. S. regula- 
tion. 


.27 


.98 


20,400 


77,097 


.25 


5.00 


15,000 




.27 


.98 


19,400 


73,318 


.25 


5.00 


15,000 




.23 


1.00 


17,200 


74,782 


.25 


4.00 


14,000 




.235 


1.00 


18,000 


7fi,595 


.25 


4.00 


14,500 




.23 


1.00 


16,400 


71,304 


.3125 


4.00 


14,000 




.225 


1.00 


15,800 


70,222 


.3125 


3.30 


13.500 


• 



BESSEMER STEEL PLATES. 



43 



TABLE VIII. 

TENSILE STRENGTH OF 70,000 POUND STEEL BOILER PLATE, MADE BY 

HUSSEY, HOWE & CO., PITTSBURG, PA. TESTS 

BY MR. ATKINSON. 













WEIGHT 




SAMPLE. 


BREAK- 
ING 
WEIGHT. 


TENSILE 

STRENGTH 

PER 

SQUARE 

INCH. 


ELONGA- 
TION IN 
PARTS OF 
AN INCH. 


TIME 

CONSUMED 

IN TEST, IN 

MINUTES 

AND 
SECONDS. 


ON THE 
MACHINE 
AT 
WHICH 
ELONGA- 
TION 
COM- 




THICK- 
NESS. 


WIDTH. 


REMARKS. 














MENCED. 














MIN. SEC. 






.25 


1.00 


18,300 


73,200 


.25 


4.G0 


16,500 


Short specimen 


.25 


1.00 


19,000 


76,000 


.1875 


4.30 


17,000 


U. S. regula- 
tion. 


.25 


1.00 


18,000 


72,000 


.25 


3.30 


17,000 




.25 


1.00 


18,500 


74,000 


.25 


4.00 


17,200 




.25 


1.00 


18,800 


75,200 


.25 


4.00 


17,400 




.25 


1.00 


17,800 


71,200 


.25 


3.30 


16,500 




.S5 


1.00 


17,600 


70,400 


.1875 


3.30 


16,000 




.25 


1.00 


18,400 


73,600 


.1875 


4.00 


17,000 





Bessemer steel is made by first melting in a cupola a 
charge of about six tons of pig iron rich in silicon and low 
in phosphorus; this molten metal is conducted by a suit- 
able trough and allowed to flow into a large vessel called 
a " converter" — the details of its construction being such 
that air may be blown up through a perforated tuyere box 
placed in its bottom, thus compelling these jets of air to 
pass up through the molten metal. The oxygen in these 
jets of air having a greater aflS.nity for the silicon than for 
anything else in the converter combines with it first and 
causes the charge to " work hot," after which the carbon 
begins to burn, and, as described by Mr. Ilolley, "the vol- 
ume and brilliancy of the flame increase and the surging 
mass grows hotter and boils over in splashes of fluid slag; 
the discharge is a thick, white, roaring, dazzling blaze,. 
and the massive vessel and its iron foundations tremble 



44 A TREATISE ON STEAM BOILERS. 

under the violent ebullition. Towards the close of the 
operation the flame becomes thinner, and when decarbon- 
ization is complete it suddenly contracts and loses illu- 
minating power. The determination of this period is the 
critical point of the process. Ten seconds too much or 
too little blowing injures or spoils the product At the 
proper instant, as determined best by the spectroscope or by 
colored glasses, but usually by the naked eye, the foreman 
turns down the vessel and shuts off the blast. The charge 
of melted spiegel-eisen is then run in, when another 
flaming reaction occurs. The vessel being still further 
depressed, the steel runs into the ladle, pure, white and 
shining, from under its coating of red hot slag. A 
blanket of slag, most useful in preserving its temperature, 
follows it into the ladle. The metal is now led into the 
ingot moulds. After the exterior surface of the steel has 
crystallized, the mould is removed and the ingot is ready 
for reheating and rolling." 

The time occupied in the conversion is about twenty 
minutes or until the carbon is exhausted. As already 
stated, a pig iron is selected rich in silicon; from two to 
two and a half per cent being the usual quantity. The 
oxidation of the silicon and carbon is, to a certqiin extent, 
done at the expense of the quality of the iron in the con- 
verter, which takes up more or less oxygen; the effect of 
this oxide of iron is to render the whole mass red-short, a 
property which may be corrected by the addition of man- 
ganese. This is supplied in the melted spiegel-eisen run 
into the converter after the " blow." The quantity admit- 
ted depends upon the required quality of the product. If 
the steel is to be low in carbon, less spiegel-eisen is intro- 
duced than if a higher steel is wanted. In practice, from 
eight to ten per cent is added. 



BESSEMER STEEL PLATES. 45 

The manganese also improves the product by neutral- 
izing the deleterious effect of any sulphur that may be 
present, and by preventing ebullition of the metal when 
poured into the ingot moulds. 

The following is an average analysis of the pig iron 
used at the works of the Cambria Iron Company in making 
Bessemer steel and well represents, in average composition, 
what is generally known in the market as Bessemer pig : 

Silicon 2.50 percent. 

Carbon 4.00 per cent. 

Sulphur 0.022 percent. 

Phosphorus 0.08 to 0.10 percent. 

6.602 
[Iron by difference 93.398] 

100.000 

The phosphorus may be reduced to 0.07 per cent when 
required for special steel. 

The spiegel-eisen made by this company consists 
average composition of 



in 



Manganese 15 

Carbon 4.3 

Silicon 0,3 

Phosphorus 0.08 

The quantity of manganese may be varied from six to 
thirty per cent, according to the special use for which it is 
required. 

Analysis of the two samples of American spiegel-eisen 
made at ITewark, New Jersey, by the New Jersey Zinc 
Company : 



46 



A TREATISE ON STEAM BOILERS. 







TABLE 


IX. 






SAMPLES. 


A 


B 


Iron 


83.250 

11.586 

0.196 

0.367 

4.632 


83 22 


Manganese 


11 67 


Phosphorus 


19 


Silicon 


99 


Carbon 


4 03 














100.031 


100.10 



As no phosphorus is removed from the iron hy the 
Bessemer process, it is important to select a pig iron 
containing less of this impurity than may be safely allowed 
in the steel. 

Manganese has the effect to neutralize the hardening 
action of phosphorus as well as to neutralize the red-short 
tendency due to the oxide of iron in the converter and 
when it does not exceed one per cent it has a toughening 
effect on the whole mass of metal. 

Bessemer boiler plates should be low in carbon, silicon 
and phosphorus, and may contain 0.5 to 0.8 per cent of 



manganese. 



Bessemer steel is now largely employed in England in 
the construction of steam boilers. Whatever doubts may 
have been expressed as to its reliability in years past, 
there seems now to be no doubt of its entire suitability for 
boiler plates. When the Bessemer process was new, work- 
m.en had to be educated to a new business and there was 
then much less of strictly scientific control in the manage- 
ment than at present. The material itself, the process of 
manufacture, the special machinery required, were all new 
and it would be contrary to human experience if the pro- 
duct was not variable in quality. 



BESSEMER STEEL PLATES. ^ 47 

The Bessemer process is now well understood and there, 
is no lack of specially trained workmen under the direc- 
tion of men who have had a scientific training. The result 
is, the production of a low priced steel of any desired 
character, practically uniform in quality, which can be 
furnished with scarcely any limitations as to quantity. 
The one thing lacking heretofore in this steel has been 
uniformity. Manufacturers, by a careful selection and 
manipulation of materials, have practically solved that 
problem so that uniformity may be said to be under as 
thorough control in this as in any other process. 

The chemistry of steel making is wholly in the hands of 
the manufacturer. How much carbon, manganese, etc., 
it shall contain is seldom or never fixed b}' the customer, 
who, except in very rare instances, must work whatever 
material the maker of the steel thinks is best suited to any 
particular use, the recourse of the purchaser being in the 
rejection of plates which do not come up to certain pre- 
scribed mechanical tests. These are usually the ordinary 
temper and bending tests ; and then for tensile strength, 
elongation and reduction of area under pulling stress. If 
the steel will stand these latter tests, the purchaser cares 
little about its chemical composition. 

The boiler maker, in addition to the mechanical tests 
given above, insists upon having a material which may be 
subjected to the various operations of bending, forging, 
local heating, fianging, annealing, punching, drilling and 
riveting, Avithout impairing its character and strength. 
The question whether Bessemer plates should be punched 
or drilled is still an open one and opinions are pretty 
nearly evenly divided. This is a question of considerable 
commercial importance, for if these plates are to be drilled 
in order to be safe, it practically confines their use to large 
and well equipped establishments. 



48 A TREATISE ON STEAM BOILERS. 

The practice at Crewe, England, where are located the 
extensive works of the London & E'orth- Western Railway 
Company, is to use steel exclusively for the shells of boilers. 
Mr. Webb's practice is to punch all rivet holes and then 
thoroughly anneal the plates before riveting. It was found 
that the plates over three-eighths inch lost strength by 
punching to the extent of about one-third and that the 
whole of this one-third was restored by annealing. As 
this company uses Bessemer plates in about four hundred 
locomotive boilers now in actual service, this circumstance 
alone carries great weight as an indorsement of this mate- 
rial in boiler construction. 

Bessemer steel plates have been used almost solely by 
this company for over twelve years, and it is said, with 
entire satisfaction. The anomaly of this railway com- 
pany using nothing but steel plates is of easy explanation. 
The company is not only singular in manufacturing the 
material for its permanent way and rolling stock, but it is 
equally fortunate in having a locomotive superintendent 
and works manager who is quite as much at home in 
manufacturing steel as in building locomotives, and it 
may be safely affirmed that no one else has had as much 
experience in the making and using of Bessemer steel 
plates.* The power and facility here afforded of choosing 
the most suitable standard of material for rails, axles, 
tyres and boiler plates from the different casts, may possi- 
bly account for the bold and successful lead so long held 
by the London & North- Western Railway Company in 
adopting the material that others may admire, but hold 
back from using. 

It is a practice with this company to make an analysis 
of each cast in the steel melting department. Every plate 
used in the boiler shop has a piece sheared off and sub- 
jected to certain standard bending and drifting tests, the 

* Engineering. 



. BESSEMER STEEL PLATES. 49 

latter consisting in drifting out cold, to two inches in 
diameter, a five-eighth inch hole in a strip two and a half 
inches wide. These plates have a tensile strength of 
about seventy-five thousand pounds per square inch and 
suffer an elongation of twenty-five per cent before break- 
ing. 

The following analysis and mechanical tests of English 
Bessemer mild steel are by Mr. Daniel Adamson, Manches- 
ter, England : . 

ANALYSIS. 

Iron 99.300 

Carbon 130 

Manganese 468 

Silicon 023 

Sulphur .031 

Phosphorus 037 

Not accounted for Oil 

100.000 

MECHANICAL TESTS. 

Length of specimen 10 inches. 

Breadth of specimen 2.66 inches. 

Thickness of specimen 375 inches. 

Area of specimen ; 1 square inch, 

Permanent set induced per square inch... 44,500 pounds. 

Maximum strain per square inch 67,000 pounds. 

Elongation where maximum strain is ap- 
plied 15 per cent., 

Final breaking strain on original area per 

square inch 58,000 pounds. 

Elongation 26 per cent. 

Bessemer steel has not been used to any considerable 
extent in this country in the manufacture of steam boilers. 
The writer saw at the Edgar Thompson steel works, Bes- 
semer, Pa., several large boilers made of Bessemer steel of 
their own manufacture. 

Samples of this steel were subjected to both tensile and 
torsional tests, resulting as below : 
(5) 



50 



A TREATISE ON STEAM BOILERS. 



TABLE X. 

SHOWING TESTS OF BESSEMER STEEL BLOOMS FOR BOILER PLATE, MANU- 
FACTURED BY THE EDGAR THOMPSON STEELWORKS. SAMPLES FIVE- 
EIGHTHS INCH IN DIAMETER AND ONE INCH LONG BETWEEN SHOUL- 
DERS, TESTS MADE IN THEER LABORATORY AND USING THE AUTO- 
GRAPHIC RECORDING TESTING MACHINE DESIGNED BY PROF. R. H. 
THURSTON. 



Angle of torsion , 

Moment of torsion, foot-lbs , 

Tensile strength at elastic limit 

Ultimate tensile strength , 

Per cent of elongation 

Carbon 



SAMPLES. 



282° 
312.15 
47,211 
64,271 
83.4 
0.10 



239° 
295.74 
39,751 
65,120 
64.3 
0.16 



217° 
288.46 
43,477 
65,664 
65.1 
0.15 



The following test was made similar to the above, and 
from the same grade of metal, in which the 

Angle of torsion was 254° 

Moment of torsion 313.39 foot-lbs. 

Tensile strength at elastic limit 39,751 

Ultimate tensile strength 67,295 

Per cent of elongation 70.8 

This same sample showed by chemical analysis, 

Carbon 0.12 

Silicon 0.005 

Phosphorus 0.078 

Manganese 0.761 

0.964 
[Iron, by difference 99.036] 

100.000 



BESSEMER STEEL PLATES. 



51 



Three other analyses of boiler plate gave results as 
follows : 

TABLE XL 



Carbon 

Silicon 

Phosphorus 
Manganese 
Sulphur 



(1) 



0.15 
0.018 
0.060 
0.784 
Not det. 



(2) 



0.10 
0.14 
0.69 
0.755 
Not det. 



(3) 



0.09 
0.028 
0.60 
541 
0.0394 



Two test pieces were sheared off the plates rolled for 
the boilers above referred to and sent to Mr. H. W. Born- 
traeger, superintendent of the Union Iron Mills, Pittsburg, 
Pa., who tested them on a Riehle Brothers' testing machine, 
with results as below : 

TABLE XII. 

MECHANICAL TESTS OF BESSEMER BOILER PLATE, MANUFACTURED BY 
THE EDGAR THOMPSON STEEL WORKS. TEST BY MR. BORNTRAEGER. 



SAMPLES. 


A 


B 


Length of sample 


3 inches. 

.29 inch. 

.63 inch. 

.1827 inch. 

9,000 pounds. 

49,250 pounds. 

12,350 pounds. 

67,590 pounds. 

Y6 inch, 23^ inches. 


3 inches. 


Thickness of sample 


.29 inch. 


Width of sample 


.63 inch. 


Area of sample 


.1827 inch. 


Elastic limit of sample 


9,000 pounds. 


Elastic limit per square inch 


49,250 pounds. 


Weight at which sample broke 


12,100 pounds. 


Tensile strength per square inch 


66,225 pounds. 


Elongation 


^ inch, 3 inchce. 
18% 


Elongation, per cent 







52 



A TREATISE ON STEAM BOILERS. 



TABLE XIII. 

MECHANICAL TESTS OF BESSEMER BOILER PLATE, MANUFACTURED BY 
THE EDGAR THOMPSON STEEL WORKS. TEST BY 
MR. BORNTRAEGER. 



SAMPLES. 



Length of sample 

Thickness of sample 

Width of sample 

Area of sample 

Elastfc limit of sample 

Elastic limit per square inch 

Weight at which sample broke... 
Tensile strength per square inch 

Elongation , 

Elongation per cent 



3 inches. 


3 inches. 


.36 inch. 


.40 inch. 


.62 inch. 


.65 inch. 


.2232 inch. 


.2600 inch. 


8,400 pounds. 


9,400 pounds. 


37,600 pounds. 


36,153 pounds. 


13,100 pounds. 


14,450 pounds. 


58,690 pounds. 


55,590 pounds. 


xf inch, 3 inches. 


% inch, 3 inches. 


31^ 


25^ 



Open hearth steel — This is also known as Siemens- 
Martin steel. The furnace or hearth in this process has 
usually a capacity of about eight tons. In the manufacture 
of boiler plate the charge consists of a charcoal pig iron 
selected with reference to its purity and freedom from 
silicon, sulphur, phosphorus, etc., care being taken that 
the total carbon is not of too high percentage, a N'o. 3 
foundry pig being about the right grade. This pig con- 
stitutes about twenty-five per cent of the entire charge ; 
it is melted in the hearth and brought to a very high heat, 
when charcoal blooms or other wrought iron of similar 
grade previously heated to a bright red heat are then 
immersed in the bath and allowed to dissolve in it. These 
charges are usually from six to eight hundred pounds and 
are introduced continuously every twenty or thirty min- 
utes, until the carbon in the whole mixture is brought to 
the desired point, which for boiler plate is from 0.10 to 



OPEN HEARTH STEEL. 53 



0.20 per cent, and the silicon is reduced either by fusion 
or by chemical action to the minimum amount, say from 
0.01 to 0.05 per cent. Tests are now made to determine 
the quality of the metal in the bath. This is done by 
taking out a small test ingot, which, after cooling in 
w^ater, is broken and tested. The fracture gives very good 
indications of the state of the charge. If in the judg- 
ment of the melter the metal is sufficiently refined, high 
grade ferro-manganese previously heated is now put into 
the bath and the whole mass of metal thoroughly stirred 
and then run out into a large ladle, from which it is poured 
into the ingot moulds. These ingots are then rolled into 
plates in the ordinary manner. 

The process just described is, in its salient points, the 
ordinary routine of steel making. This process allows 
considerable latitude in manipulation, so that it is to be 
expected that different manufacturers, widely separated, 
would pursue different methods of working. 

■ Carbon — The total quantity of carbon in steel plate 
made by the open hearth process may be varied to suit 
circumstances, as tests may easily be made before drawing 
the charge. Steel boiler plate having carbon in propor- 
tions varying from 0.10 to 0.20 per cent have given good 
results in practice. The latter figure is rather high to 
secure the greatest ductility and ought not to be exceeded. 
An excess of carbon increases the tensile strength of steel 
at the expense of its ductility and elasticity — hence, makers 
aim to produce a steel for boilers having a tensile strength 
of about sixty-five thousand pounds per square inch, and 
the analyses of samples so tested are found to contain from 
0.10 to 0.15 per cent of carbon ; 0.13 is found to give excel- 
lent results in practice. 

Manganese — The exact function of manganese in steel 
is not clearly nnderstood ; the belief is, however, that 



54 



A TREATISE ON STEAM BOILERS. 



it deoxidizes the bath, as well as removes the sul- 
phur. This is inferred from the disappearance of most 
of the sulphur from the iron in the bath and partly 
from the circumstance that only about one-half of the 
metallic manganese, added at the last of the charge, 
is found in the analysis of the resultant steel. An excess 
of manganese in steel boiler plate has the effect to reduce 
its ductility and elasticity, 0.25 per cent is ample for hot 
working, and good results have been obtained from steel 
plates having manganese present in the proportion of 1.50 
of manganese to 1.00 of carbon. 

The relative proportions of carbon and manganese in 
open hearth boiler plate is confined within comparatively 
narrow limits to get the best results. An excellent quality 
of plate made at differet times by the same furnace was 
found to contain, upon analysis, the following quantities 
of each : 

TABLE XIV. 





CARBON. 


MANGANESE. 


RATIO OF CARBON TO 
MANGANESE. 


A 


,10 per cent. 


17 per cent. 


1 to 1.7 


B 


.11 per cent. 


18 per cent. 


1 to 1.64 


C 


.11 per cent. 


22 per cent. 


1 to 2. 


D 


.11 per cent. 


24 per cent. 


1 to 2.18 


E 


.12 per cent. 


16 per cent. 


1 to 1.33 


F 


.12 per cent. 


17 per cent. 


1 to 1.41 


G 


.12 per cent. 


25 per cent. 


1 to 2.08 


H 


.13 per cent. 


17 per cent. 


1 to 1.30 


I 


.13 per cent. 


20 per cent. 


1 to 1.54 


J 


.13 per cent. 


23 per cent. 


1 to 1.77 



The manufacture of steel plates by the open hearth 
process in the United States dates from 1871 and attained 



OPEN HEARTH STEEL. 55 

a high degree of perfection in a short time afterward, 
as shown by the following mechanical tests made by the 
United States government to determine its suitability for 
ship building. The tests were made in 1873 by Mr. Samuel 
H. Pook, naval constructor, and F. L. Fernald, assistant 
naval constructor, United States IS'avy, The steel tested 
was made by the N'ashua Iron and Steel Company : 

The first test was made with reference to the tensile 
strength, and for that purpose two pieces were selected 
from plates having a thickness of nine-sixteenths, ten- 
sixteenths and eleven-sixteenths, respectively. These six 
pieces gave a mean tensile strain of 27.82 tons (62,316.8 
pounds) per square inch of original section ; 65.30 tons 
(146,272 pounds) per square inch of fractional section, an 
elongation of two and one-sixteenth inches in a length of 
eight inches, and a mean strain of 19.06 tons (42,694.4 
pounds) per square inch without stretch, or sixty-five per 
cent of breaking strain. The strain was the same in all 
samples and the strength was remarkably uniform. 

The cold forge tests were made with plates nine- 
sixteenths and five-eighths inches in thickness. It was 
found that the samples could be folded over until the sur- 
faces met, without any perceptible evidences of fracture. 
A nine-sixteenths inch plate was placed over a hole nine 
by nine inches square in a piece of wrought iron, a six-inch 
cast iron shot was then driven down by a two thousand 
pound steam hammer having a mean stroke of twenty-four 
inches, until the calotte or cup thus formed had a depth of 
four and three-eighths inches. The lower surface was then 
thoroughly examined and no signs of fracture could be 
detected. A second trial was then similarly made upon 
a plate eleven-sixteenths inch thick, with a view to ascer- 
tain to what extent this test could be carried without 
fracture. 



56 A TREATISE ON STEAM BOILERS. 

After breaking three shot, a wrought iron cylinder 
with a spherical end was substituted, and at about the six- 
tieth blow disintegration took place along one side of the 
cup at a distance of two inches from its bottom. The 
thickness of the plate at the point of fracture was reduced 
to one-quarter inch, the depth of the cup being four and 
seven-eighths inches. 

When heated it was found that the plate could be 
folded over until the surfaces met, and then bent in the 
opposite direction to a similar position without fracture, 
and after repeating this operation four times only a slight 
fracture took place. 

Hot tests were made also in the following manner : 

A three-quarter-inch hole was punched in a cold plate ; 
the plate was then several times heated and the hole pinned 
out until a cylinder was formed five inches in diameter and 
five inches long. After it was thoroughly cold a flange 
was turned down all around the end, the surface remain- 
ing perfectly free from cracks and other defects. 

Kight angled, inside and outside corner flanges were 
formed with the greatest ease; no amount of heating 
appeared to affect the malleability in the least. With a 
view to ascertain if the scrap which would be made in 
building a ship could be utilized, about sixty pounds of 
samples were made up into three-quarters of an inch round 
bars in precisely the same manner as ordinary iron. 

The tensile strength of this bar was found to be 29.62 
tons (66,349 pounds) per square inch, or one and one- 
eighth ton (twenty-five thousand two hundred pounds) 
more than from the original plate. Several rivets were 
made from the bar which stood a double shearing strain 
of 21.55 tons (48,272 pounds) or 48.76 tons (109,222 pounds) 
per square inch. 



OPEN HEARTH STEEL. 57 



An analysis of this steel was made by Mr. J. A. Her- 
rick in 1873. The ingot steel tested before reheating and 
rolling showed 0.14 per cent of carbon. The following is 
that of the finished plate : 

f 1320^ per cent by the chloride of copper 

^ , , , . . .„. I 0.1297 S method. 

Carbon (combined) 0.130 ■{ „ „„„\ ^ ,. . ,, . 

0.1100 by combustion in chlorine and 

[ then in oxygen. 

Carbon (graphite) none 

Manganese O.ioo 

Sulphur 0.028 

Phosphorus 0.011 

Silica 0.071 by the chlorinp combustion method. 

Iron (difference) 99.660 

Total 100.000 

The pig iron used was the Workington hematile cold 
blast charcoal, from the Cumberland district, England, and 
contained by Mr, Herrick's analysis : 

Silicon 0.360 by the chlorine combustion method. 

Slag 2.800 by the chlorine combustion method. 

Carbon (combined) 0.552 by the chloride of copper method. 

Carbon (graphite) 3.178 by the chloride of copper method. 

Sulphur .' 0.052 

Phosphorus 0.016 

Manganese 0.080 

Iron (difference) 92.962 

Total 100.000 

The charcoal blooms used in this mixture were made 
from Rodger's bed ore, Chateaugay lake, Clinton county, 
New York, and by Mr. Herrick's analysis contained : 

Silica 0.418 by the chlorine combustion method. 

Slag 0.030 by the chlorine combustion method. 

Sulphur 0.038 

Phosphorus 0.005 

Manganese trace 

Carbon 0.250 by the chloride of copper method. 

Iron (difference) 99.2.59 

Total 100.000 

The steel just described was made of a quality suitable 
for shipbuilding, and for steam boilers; tbe requirements 



58 



A TREATISE ON STEAM BOILERS. 



being in all essentials the same for the two kinds of service. 
It shows remarkable toughness, combined with a reason- 
able tensile strength. 

The following tests by Mr. Richards were made on the 
same kind of steel, but manufactured in another section 
of the country: 

TABLE XV. 

SHOWING THE EFFECTS OF TENSILE STRAINS ON SEVERAL SAMPLES OF 
STEEL PLATES RECEIVED JANUARY 15, 1875, FROM THE OTIS IRON AND 
STEEL COMPANY, OF CLEVELAND, OHIO, AND TESTED FOR THEM BY 
C. B. RICHARDS, ENGINEER, HARTFORD, CONN. 

Long Specviaens. 



I 







ORIGINAL 1 


MINI- 








ft 

o 
p 
ft 

o . 






1 










MUM CROSS 
SECTION. 


'A 
< 

O 


LENGTHS. 


5r. 
< 


a 
< 


EB SQUARE 
MINIMUM 

N. 


o 

H 
o 

a 




« 






►i c^ 

S D ft 


as 

D 


S5 
O , 


a 


CO 






H r 1 


. a: hJ 


H 


S t^ 


65 


c 


0- c 


CO ^ 


O 


D 

CO 


< 

t3 


m 

2; 

o 

5 


< 

< 




LENGTH 01 
CTION, MEA 
N THE SHOU 


< 

Pi 

&^ 
•< 


a a 
^^ 

""J a 
Oi cu 


CO 

z; 


CO 

a 
13 


STRENGTH 
3P ORIGINAL 
CROSS SKCTI 


!2i 

O 

a 
a 
-"I 




< 


a 


SQ.IN. 


O 
< 

a 

B3 


ORIGINAL 
MUM SE 
UETWEE 


t-l 


< 
a 

h5 


M 


o 
H 

CO 


a 
a 


O 

ft 

a 

05 








INCH. 


SQ.IN. 


INCHES 


in's 


LBS. 


LBS. 


LBS. 


LBS. 


p. CT. 


p. CT. 


506 


28.28. 
X 


1.00x0.375 


0.375 


0.133 


10.0 


11.55 


10,000 


21,120 


27,C0:) 


56,320 


65.0 


15.5 


507 


28.28. 
X 


1.00x0.375 


0.375 


0.131 


10.0 


11.50 


12,000 


20,900 


32,000 


55,733 


65.0 


15.0 


508 


28 


1.00x0.350 


0.350 


0.144 


10.0 


11.48 


9,000 


20,140 


26,000 


57,543 


59.0 


14.8 


509 


28H 


1.00x0.350 


0.350 


0.200 


10.0 


10.70 


10,000 


27,680 


29,000 


79,086 


43.0 


7.0 


510 


12 


1.00x0.300 


0.300 


0.105 


10.0 


11.68 


10,000 


16,900 


33,000 


56,333 


65.0 


16.8 


512 


32 


1.00x0.312 


0.312 


0.117 


80 


9.58 


12,000 


17,900 


38,000 


57,371 


62.5 


19.8 


514 


7 


1.00x0.323 


0.323 


0.117 


8.0 


9.73 


13,000 


18,230 


40,000 


56,440 


63.0 


21.6 


516 
518 


38 


1 00x0 325 


325 


148 


8 


9 49 


9,000 
12,000 




28,000 
38,000 




54.5 


18.6 


38 


1.00x0.325 


0.325 


0.159 


8.0 


9.31 


22,715 


62,470 


51.0 


16.2 



OPEN HEARTH STEEL. 



5^ 



TABLE XV— Continued. 

Short Specimens. 





< 

P 
H 
O 


ORIGINAL MINI- 
MUM CROSS 
SECTION. 


a 

H 

a 

<! 

o 

H a 

H ;:> 

CO <J< 

< « 

a 
o 

< 
a 

« 


LENGTHS. 




a 
p 

o . 

OS H 

b ^ 

CO 

is 

^^ 

sl 

< a 

« Oh 
H 

CO 

<! 

a 
1^ 


< 

CS 
CO 

CS 

"A 
>-* 

w 

<! 

a 
« 
n 


a 

u 

•A 

a 

P5 
<! 

p 

CO 

a 
o 

M 

H 
CO 

<! 

a 


TENSILE STRENGTH PER SQUARE 

INCH OF ORIGINAL MINIMUM 

CROSS SECTION. 


« 

o 
t-i 

H 
O 

a 

M 

CO a 
§ 2 

®H 

!?; 

O 

o 

P 
Q 

a 




n 
% 

H 

W 
H 


oi 

;?; 
o 

CO 

a 

Q 


< 
a 

PS 


ORIGINAL LENGTH OF MINI- 
MUM SECTION, MEASURED 
BETWEEN THE SHOULDERS. 


a 
p 

H 

< 
a 

« 
a 

a 

w 

a 


•a 
o 

M 

< 

;z; 
O 

>-! 

a 
a 

EH 

■< 

1-3 
P 


511 


12 

32 

7 

38 


INCH. 

1.00x0.310 
1.00x0.311 
1.00x0.323 
1.00x0.325 


SQ.IN. 
0.310 

0.311 

0.323 

0.325 


SQ.IN. 
0.151 

0.132 

0.154 

0.159 


INCHES 









in's. 


lbs. 


LBS. 
19,800 

20,330 

21,660 

22,715 


LBS. 


LBS. 
63,871 

65,370 

66,935 

69,277 


P.CT_ 
52.0 ' 

58.0 

52.4 

51.0 


P.CT.. 


513 










515 






517 




















The numbers obtained by dividing the breaking strain 
by the area of least section after fracture, sometimes called 
''the tensile strength per square inch of fractured area," give 
a valuable measure of the toughness of the material. 
These numbers are as follows, for the several specimens : 



No. 506 159000. 

No. 507 160000. 

No. 508 140000. 

No. 509 138000. 

No. 510 161000. 

No. 511 131000. 



No. 512 .153000. 

No. 513 155000. 

No. 514 155000. 

No. 515 140000. 

No. 517 143000. 

No. 518 166000. 



The strains were applied gradually in all cases. 

With specimen Fo. 516, the breaking strain was not 
observed; but ]^o. 518, of the same material, was after- 
ward broken and the result recorded. 



60 A TREATISE ON STEAM BOILERS. 



REMARKS BY OTIS IRON AND STEEL COMPANY. 

The above samples contained the following percentages of combined carbon : No. 
28, .0014 per cent ; No. 12, .0013>^ per cent; No. 32, .0014 per cent; No. 7, .0012 percent; 
No. 38, .0014 per cent. 

Samples marked ^^^^^' were taken from across the sheet. 

Sample marked 28 H was heated red hot and cooled in water before being broken, and 
although the strength is increased, there is no perceptible increase in the hardness when 
tried with the file. 

Samples No. 28, No. 12, No. 32, No. 7, were uniform in mixture and quality of stock 
used. 

Several very severe mechanical tests, to show the qual- 
ities of open hearth homogeneous boiler plate, were made 
with cold plates at the works of this company at Cleve- 
land, Ohio, in the presence of the writer, to whom the 
samples were also given. The pieces tested were sheared 
off the ends of plates, which were then being cut to dimen- 
sions in their ordinary business routine. 

Several unannealed samples from plates five-sixteenths 
of an inch thick were folded down in the usual manner by 
blows given by a heavy hammer. Samples were also sub- 
jected to a shearing test, in which a piece of steel three 
inches in width was sheared up to within an eighth of an 
inch of the edge without exhibiting any signs of fracture, 
the "shearing" being depressed more than half an inch on 
the opposite edge of the plate. A number of these " shear- 
ings" were made at a distance of about five-eighths of an 
inch apart. A sample about eight inches square, taken oft 
another plate selected at random on the floor of the mill, 
was folded over fiat and afterward folded again at right 
angles to the first, the whole being then hammered flat, 
making a specimen about four inches square and one and 
a quarter inches thick, without exhibiting any signs of 
fracture. 

A selection of five tests was taken from their labora- 
tory record to show the range in tensile strength allowable 
in this system of manufacture. The tests were made with 
the ordinary two-inch specimens, with results as follows: 



OPEN HEARTH STEEL. 



61 



TABLE XVI. 

SHOWING THE RANGE IN TENSILE STRENGTH OF OPEN HEARTH STEEL 
PLATES MADE BY THE OTIS IRON AND STEEL COMPANY. 











i% 




<y «H 














CO Z 












I OF M 
EASUK 
LDERS. 


g 

5 


H PER 
AL MI 
ION. 


o 

H 


o 

H 

Oi 


o 

H 

i-i 
» 

M 


o 

M 

Q 




INAL LENGTI 
UM SECTION M 
TWEEN SHOU 


05 
w 
C5 

< 


5ILE STKENGT 
DH OF ORIGIN 
M CROSS SECT 


O 

a 
a 










o g a 


ca 


Szg 


H 










5-« 




H M S 


iJ 










o 




(^ 


P 




PLATE. 






INCHES. 


POUNDS. 


POUNDS. 


PER CT. 


877 


Vs 


.98X.374 


.366 


2. 


16,300 


44,530 


49 


1501 


^ 


.986X.319 


.315 


2. 


18,200 


57,770 


44 


1879 


% 


.913X.37 


.339 


2. 


21,300 


62,830 


34 


1521 


y^ 


.64X.519 


.332 


2. 


23,750 


7J,530 


33 


1905 


M 


.851X.25 


.213 


2. 


17,975 


84,390 


25 



The first line in the above table shows the remarkably 
low tensile strength of forty-four thousand five hundred 
and thirty pounds per square inch. It is seldom that steel 
is made so lo.w as that; and is less than is to be recom- 
mended for boilers, as such plates are apt to be spongy. 
The last line in the table showing eighty-four thousand 
three hundred and ninety pounds tensile strength, is less 
ductile, as will be observed by comparing the percentages 
of elongation — the ratio being twenty-five to forty-nine 
per cent. This latter grade of metal is too high for boil- 
ers; sufifering more in punching, lacking in ductility and 
is more likely to be brittle than steel ranging from sixty 
thousand to seventy thousand pounds. 



62 



A TREATISE ON STEAM BOILERS. 



TABLE XVII. 

TENSILE STRENGTH OF 60,000 POUNDS OPEN HEARTH STEEL, MADE BY 

SINGER, NIMICK & CO., PITTSBURG, PA. TESTS 

BY MR. ATKINSON. 















WEIGHT 




SAMPLE. 


BREAK- 
ING 
WEIGHT. 


TENSILE 

STRENGTH 

PER 

SQUARE 

INCH. 


ELONGA- 
TION IN 
PARTS OP 
AN INCH. 


TIME 

CONSUMED 

IN TEST, IN 

MINUTES 

AND 
SECONDS. 


ON THE 
MACHINE 
AT 
WHICH 
ELONGA- 
TION 
COM- 




THICK- 
NESS. 


WIDTH. 


REMARKS. 














MENCKD. 














MIN. SEC. 






.25 


.98 


15,000 


61,224 


.3125 


8.30 


12,000 


Short specimen 


.25 


.98 


15,400 


62,857 


.25 


3.80 


12,500 


U. S. regula- 
tion. 


.25 


.98 


16,400 


66,938 


.25 


4.00 


13,500 




.25 


.98 


15,000 


61,224 


.25 


3.00 


12,000 




.25 


.98 


16,000 


65,306 


.25 


4.00 


12,500 




.25 


.98 


15,300 


62,449 


.25 


3.30 


12,000 




.25 


.98 


15,500 


68,265 


.25 


4.00 


12,000 




.25 


.98 


15,700 


64,081 


.25 


4.00 • 


12.500 





This table and the one following is, so far as tensile 
strength is concerned, the grade of steel recommended for 
boiler making, and if the steel is properly made it ought 
to be able to withstand all the mechanical tests ordinnarily 
demanded in construction. Test pieces in tables XVI, 
XVII and XVIII were as shown in figure 2. 



1 inch. 



■^y 



1 inch. 
FlUUSE 2. 



OPEN HEARTH STEEL. 



63 



TABLE XVIII. 

TENSILE STRENGTH OF 65,r00 POUNDS OPEN HEARTH STEEL MADE BY 

SINGER, NIMICK & CO., PITTSBURG, PA. TESTS BY 

MR. ATKINSON. 



SAMPLE. 


K 

s 



l-H 

a 


C6 
P- 
K 

M [a 


< 




CO 

H . 

P ^ 
cc . 
12; 52; 

s 
B :^ 

1— ( 


WEIGHT ON MACHINE AT 
WHICH ELONGATION 
COMMENCED. 




06 

W 

H 


K 

H 
Q 


REMARKS. 


.25 


1.00 


17,500 


70,000 


.25 


MIN. SEC. 
4.00 


13,500 


Short speci- 


,25 


1.00 


16,800 


67,200 


.25 


3.30 


13,500 


men U. S. 
regulation. 


.25 


1.00 


17,300 


69,200 


.25 


4.00 


14,000 




.23 


1.00 


15,700 


68,260 


.25 


3.00 


13,000 




.235 


1.00 


15,800 


67,234 


.25 


3.30 


13,000 




.23 


.98 


14,800 


65,661 


.25 


3.00 


13,000 




.235 


1.00 


.15,400 


65,531 


.25 


3.30 


13,000 




.235 


1.00 


15,900 


67,659 


.25 


3.30 


13,000 




.23 


1.00 


15,200 


66,086 


.25 


3.00 


13,000 




.23 


1.00 


15,300 


66,522 


.25 


3.00 


13,000 




.235 


1.00 


15,400 


65,531 


.25 


3.00 


13,000 




.23 


1.00 


15,000 


65,217 


.25 


3.00 


13,000 




.235 


1.00 


16,200 


68,936 


.25 


3.00 


13,000 





The next table (XIX) gives the tensile strength of ten 
samples of seventy thousand pound steel. This tensile 
strength ought not to be exceeded in boiler plates, as plates 
of higher strength are more liable to fracture, are less duc- 
tile and more likely to harden than the lower grades. 



64 



A TREATISE ON STEAM BOILERS. 



TABLE XIX. 

TENSILE STRENGTH OF 70,000 POUNDS OPEN HEARTH STEEL, MADE BY 
SINGER, NIMICK & CO., PITTSBURG, PA. TESTS BY 
MR. ATKINSON. 



SAMPLE. 


■ o 

< 


- tf 

ft, 

« H 


03 

EH 

(^ . 

K 
12; o 

2 < 

!^ 
C 
_] 

a 


H 

DO 
W 

H d 

O Q 

o S 

1— 1 
H 


WEIGHT ON MACHINE AT 
WHICH ELONGATION 
COMMENCED. 




. 02 
!2i 

w 




REMARKS. 


.23 
.23 


.99 
.99 


16,400 
16,100 


72,400 
70,707 


.3125 
.25 


MIN. SliC. 

5.00 
5.00 


11,500 
11,500 


Short speci- 
men U. S. 
regulation. 


.23 


.99 


16,500 


72,463 


.25 


5.00 


12,500 




.225 


.99 


15,700 


70,482 


.3125 


4.30 


11,500 




.225 


.98 


15,500 


70,294 


.3125 


4.00 


12,000 




.23 


.99 


16,400 


72,024 


.25 


5.00 


12,500 




.23 


1.00 


17,400 


75,652 


.25 


5.30 


12,500 




.23 


1.00 


17,300 


75,217 


.25 


4.30 


12,000 




.225 


.99 


15,700 


70,482 


.25 


4.00 


11,500 




.225 


.99 


15,800 


70,931 


.25 


4.00 


11,500 





The following is taken from a valuable and interesting 
paper on ''The properties of iron and steel," by Daniel 
Adamson, C.E., Manchester, England. 

SIEMENS-MARTIN STEEL. 

ANALYSIS. 

Iron 99.224 

Carbon , 200 

Manganese 500 

Silicon 009 

Sulphur 035 

Phosphorus 032 

100.000 



OPEN HEARTH STEEL. 65 



MECHANICAL TESTS. 

Length of specimen 10 inches. 

Breadth of specimen 2.06 inches. 

Thickness of specimen 485 inch. 

Area of specimen 1.0 square inch. 

Permanent set induced per square inch 34,500 pounds. 

Maximum strain per square inch 59,500 pounds. 

•Elongation when maximum strain is ap- 
plied- 16.5 per cent. 

Pinal breaking strain on original area per 

square inch 50,500 pounds. 

Elongation 27 per cent. 



(6) 



CHAPTER V. 



TESTING WROUGHT IRON OR STEEL FOR BOILERS. 

Bending Tests — Temper Test — Drifting Test — Tensile Strength — 
Sizfe and Shape of Samples for Testing — Long and Short Specimens 
— French, English and American Practice — Elongation — Reduction 
of Area — Elastic Limit — Percussion Tests — Bulging Tests — English 
Admiralty Tensile and Forge Tests for Boiler Plate — Mr. Kirkaldy 
on Testing Iron. 

Testing wrought iron or steel for boilers — The tests to 
which these materials of constraction are subjected are 
both cold and hot. 

Bending test — The simplest and at the same time a most 
satisfactory test is to shear off a strip of any conv.enient 
width, say, one to two inches, and bend it down cold with 
a sledge hammer until the plates touch, as shown in figure: 




Figure 3. 



Very few irons, except the better grades of flange iron, 
will stand a test of this kind. In the manufacture of steel 
plates this is the ordinary mill test, and it is the practice of 
all reputable manufacturers to reject any plate five-six- 
teenths of an inch thick and less which will not stand this 
test without breaking. 

The temper test (for steel) consists in shearing a similar, 
strip from a plate and heating it to a low cherry red heat 



TESTING BOILER PLATES. 67 

and suddenly quenching in water, allowing it to remain 
there until cold and then bending the sample over double 
until the diameter of the inner curve is from two to three 
times the thickness of the plate, without exhibiting any 
signs of fracture. The former bending test is not so effect- 
ive as this, for the reason that it might not detect a hard 
plate that had been well annealed before shearing, but by 
tempering the strip the hard and comparatively brittle 
niature of the plate immediately discloses itself. 

The drifting test consists^ in shearing samples two and 
■one-half inches wide and punching a five-eighth inch hole 
in the center, annealing thoroughly and "drifting" the 
hole out with taper pins. The larger the hole the better 
the material ; it is expected that ordinary steel plates will 
^* drift" to twice the diameter of the punch without show- 
ing any signs of fracture. Mr. Webb's standard, at Crewe, 
Eng., is to drift the f-hole out to two inches in diameter 
for any Bessemer plates entering into locomotive boilers. 

Tensile strength — The tests for tensile strength consists 
in preparing a specimen similar to figure 4, having an area 



of least cross section i v ^ /" 

of one-fourth of one 
square inch. This spec- 
imen is adjusted in a > ^ 

testing machine and figure 4. 

weights added until it breaks. This breaking weight, mul- 
tiplied by the original fractional area of the specimen, is 
taken as the tensile strength per square inch of the mate- 
rial tested. 

The lowest grade of wrought iron, entering into the 
€onstruction of the shells of steam boilers, should stand a 
tensile strain of at least 45,000 pounds per square inch. 
The best irons range from 60,000 to 75,000 pounds and 
occasionally higher. 



68 



A TREATISE ON STEAM BOILERS. 



For steel boiler plates the tensile strength is to he kept 
as low as possible and insure sound and homogeneous 
ingots or plates. In crucible steel it is difficult to get it 
below sixty thousand pounds and should not exceed 
seventy-five thousand. In Bessemer and Siemens-Martin 
steels it may vary from fifty-five thousand to seventy 
thousand pounds. 

TABLE XX. 

STRENGTH OF AMERICAN IRON BOILER PLATE. TESTS MADE AT THE U. S. 
TREASURY DEPARTMENT, WASHINGTON. 





THICKNESS 


TENSILE STRAIN 


REDUCED 




NO. 


IN 


IN POUNDS PER 


AREA PER 


HOW TESTED. 




INCHES. 


SQUARE INCH. 


CENT. 




128 


i 


61,538 


36 


With the grain. 


129 


i 


59,125 


18 


Across the grain. 


136 


k 


58,373 


38 


With the grain. 


135 


i 


53,333 


9 


Across the grain. 


126 


5 


62,871 


38 


With the grain. 


127 


T^ 


58,765 


20 


Across the grain. 


134 


5 
TS 


62,195 


43 


With the grain. 


133 


5 
T6 


60,202 


10 


Across the grain. 


124 


f 


61,481 


30 


With the grain. 


125 


1 


58,653 


22 


Across the grain. 


132 


3 
8 


60,408 


47 


With the grain. 


131 


3 
8 


57,377 


15 


Across the grain. 


148 


3 

8 


56,270 


25 


With the grain. 


149 


1 


54,461 


17 


Across the grain. 


146 


^ 


61,918 


33 


With the grain. 


147 


i 


63,469 


6 


Across the grain. 



Nos. 128, 129 were one-fourth inch iron reduced to the square of its thickness. Nos. 
135, 136 were of the same iron and were nearly one inch wide. Nos. 126, 127 were of small, 
and 133, 134 were of larger area. Nos. 124, 125, 148, 149 were cut exactly the square of the 
thickness, and Nos. 131, 132 were of the same iron whose area approximated one-fourth of 
one square inch. Nos. 146 and 147 were samples of one-half inch, cut the square of its 
thickness. 

It may be of interest to compare the relative tensile 
strengths of American with English boiler plates. The 



ENGLISH BOILER PLATES. 



69 



figures in table XXI it will be observed, average consider- 
ably lower in the table immediately preceding. One thing 
in favor of the figures given of any tests made in England 
is, that test pieces are as a rule eight or ten inches long, 
while in this country they are usually the "short," though 
sometimes two inches long, and rarely six or eight inches, 
a|difl:erence which will be explained further along in this 
chapter. 

TABLE XXI. 

TENSILE STRENGTH AND DUCTILITY OF ENGLISH BOILER PLATE, AS 
DETERMINED BY MR. KIRKALDY'S EXPERIMENTS. 



DISTRICT IN 

WHICH THE IRON 

IS MADE. 


NAMES OF MAKERS 
OR WORKS AND BRANDS. 


DIRECTION 

OF THE 

GRAIN AND 

THICKNESS 

IN 

INCHES. 


TEARING 
WEIGHT 
PER SQ. 
INCH OF 
ORIGINAL 
SECTION 
IN LBS. 


CONTRAC- 
TION OF 
AREA 
FRAC- 
TURED. 
PERCENT 


ULTI- 
MATE 

ELONG- 
ATION 

OR TEN- 
SILE 

SET AF- 
TER 
FRAC- 
TURE. 

PER CT. 


Yorkshire 


Lo wni oor 


T 5 
L. T6 

c. ^ 

L. f 

c. f 

L. f 

c. 1 

L. i 

c. i 

L. T6" 

L. f to 1^ 
C. f to ^ 
L. 1 
C. 1 
L. i to f 

c. i to f 


5] ,990 

50,512 

56,000 

46,211 

52,237 • 

46,435 

.55,821 

50,445 

54,835 

45,584 

44,957 

44,021 

.51,2.51 

46,704 

53,402 

41,776 


19.7 

12.1 

17.8 

13.2 

15.3 

6.9 

17.2 

9.0 

12.5 

4.6 

8.7 

69 

13.1 

10.2 

10.6 

3.7 


13.2 


Yorkshire •. 


Lowmoor 


9.3 


Yorkshire 


Farnley 


14.1 


Yorkshire 


Farnley 


7.6 


Yorkshire 


fiowling. 


11.6 


Yorkshire 


Bowling 


5.9 


Staffordshire 


Bradley % Crown S. C 

Bradley % Crown S. C 

Thorney croft, Best Best 

Thorney croft, Best Best 

Lloyds, Foster, %, Best.... 
Lloyds, Foster, %, Best.... 
Consett, Best Best. 


12.5 


Staffordshire 


5.5 


Staffordshire 


11.2 


Staffordshire 


4.6 


Staffordshire 


5.3 


Staffordshire 


4.6 


North of England... 


8.9 


North of England... 


Consett, Best Best 


6.4 


Scotland 


Glasgow, Best Best 


9.0 


Scotland 


Glasgow, Best Best 


2.6 









L. signifies lengthwise, or in the direction of the grain. 
C. signifies crosswise, or across the grain. 



70 A TREATISE ON STEAM BOILERS. 

This subject has received a great deal of attention in 
England, and I quote from a paper by Mr. Marlett, chief 
examiner, Lloyd's Register, 1878, as follows: 

"Another point of our investigations which has 
received our most anxious attention, is as to the limits 
within which the tensile strength should be confined. 

" In the committee's circular, the limits are from twenty- 
six to thirty tons (58,240 to 67,200 lbs), and this agrees with 
the Admiralty requirements, but the weight of evidence we 
have been able to collect since the issue of that circular is 
in favor of somewhat higher limits. Mr. Sharp, of the 
Bolton Co., Mr. Webb, of Crewe, and Mr. Ellis, of Messrs. 
J. Brown & Co.'s works, urge that the upper limit might 
be raised to thirty-two tons (71,680 pounds) per square 
inch, without the slightest fear of obtaining brittle plates, 
so long as the temper and other tests are enforced. The 
Dutch government stipulate for a tensile strength of from 
twenty-seven to thirty-one tons (60,480 to 69,440 pounds) 
in their present contracts with the Bolton and Landore 
steel companies, and in contracts for boiler plates and 
other uses, the limits are fixed as high as thirty-three tons 
73,920 pounds), although the steel has still to be mild and 
ductile. It is said by some that when steel gets down to 
about twenty-six tons (58,240 pounds) in tensile strength, 
it begins to be more spongy and is less capable of being 
welded than steel of twenty-eight tons (62,720 pounds) 
per square inch, and it is urged that steel between thirty 
and thirty-two tons (67,200 to 71,680 pounds) strength, if 
it fulfills all the other conditions of ductility, is abetter 
material than the weaker, and sometimes less ductile, 
material having a tensile strength of twenty-six tons 
(58,240 pounds). Indications seem to show that these lower 
limits are more easily reached by the Siemens steel than 
by the Bessemer and an advantage is claimed for the lat- 
ter at the higher limits. After giving the matter our most 



SIZE AND SHAPE OF SAMPLES. 



71 



carefal consideration, we are of the opinion that it would 
on the whole be preferable to fix the limits at twenty-seven 
to thirty-one tons (60,480 to 69,440 pounds) per square 
inch, rather than twenty-six to thirty tons (58,249 to 67,200 
pounds)." 

The size and shape of samples for testing — It was but a 
few years since that the only experimental test to which 
boiler plate was subjected was to determine its tensile 
strength. It was then the custom to make test pieces 
short, or, rather, of no particular length, and with little or 
no uniformity of cross section, except at the point where 
rupture was to occur. The pieces were, however, usually 
of one of the outlines, as given in the accompanying 
sketches, in which figure 5 is designated as a long and fig- 
ure 6 as a short specimen : 



X. 



J- 



Figure 5. 




Figure 6. 



In testing a plate to determine its tensile strength 
merely, this is perhaps well enough; but as nearly all tests 
are now required to show both tensile strength and ductil- 
ity, it is recommended that test pieces be of the same 
length and sectional area, in order that results of different 
tests may be tabulated, and thus form an intelligent and 
ready means of comparison, preventing much needless con- 



72 A TREATISE ON STEAM BOILERS. 



fusion, which must necessarily arise where specimens are 
of different lengths. 

Experiments made to determine how the different 
lengths of specimens tested affects the percentage of elong- 
ation, show most clearly that if a fixed percentage of elong- 
ation is required, the specimen should be of fixed length. 
If, on the other hand, latitude is permitted in the length of 
the specimens to be tested, so as to suit the different test- 
ing machines, there should be a sliding scale for percentage 
of elongation. The different percentages of elongation for 
different lengths of specimens were found by experiment to 
be as follows : * 

STRETCH 6f homogeneous STEEL PLATES, 

Eight inch specimen 20 percent. 

Six inch specimen 25 percent. 

Four inch specimen 32 percent. 

Two inch specimen 37^ percent. 

The reason for these differences of percentages in elong- 
ation is obvious, and arises from the fact that near the 
point of fracture the elongation is much greater than at 
other parts of the specimen. With material, therefore, of 
equal quality, the shorter the specimen tested the higher 
will be the percentage of elongation; or, on the other 
hand, comparatively hard and brittle steel might easily be 
made to show a required twenty per cent of elongation by 
making the specimen sufficiently short for the purpose. 

In testing samples of steel boiler plate it is of the 
utmost importance that the pull be exactly in the line of 
the sample, so that when fracture sets in, it shall be a break 
and not a tear. A material may be torn asunder at a 
pressure very much below^ that required to break it or pull 
it apart. Care should also be taken that no imperfections 
or "nicks" exist in the test portion of the sample. 

'•■ Committee Report, Lloyd's Begister. 



UNITED STATES GOVERNMENT TESTS. 73 

The eight inch specimen was first adopted by the 
French Admiralty and afterward by the English Admir- 
alty, then by Lloyd's Register of English and Foreign 
Shipping, and thus a standard length forced itself upon 
the attention of manufacturers, so that it is now in very 
general use in Europe. It is much to be regretted that 
our own government still uses the short test specimens, 
particularly as little or no modifications would be required 
in the present testing machines in order to use the eight 
inch specimen. This would enable a direct comparison of 
American and foreign tests, which are always of great 
interest and value. 

TJ. S. Government Tests — The instructions to local 
inspectors of steam boilers, so far as relates to the ten- 
sile strength of boiler plate, and contained in the rules 
and regulations prescribed by the Board of Supervising 
Inspectors of steam vessels, are as follows: 

" Rule 3 — Every iron or steel plate intended for the con- 
struction of boilers to be used on steam vessels shall be 
stamped by the manufacturer in the following manner, 
viz: At the diagonal corners, at a distance of about four 
inches from the edges, and also at or near the center of the 
plate, with the name of the manufacturer, the place where 
manufactured and the number of pounds tensile strain it 
will bear to the sectional square inch. 

"When a sheet of boiler iron is found by the inspector 
with one or more stamps upon the same, the inspectors 
shall in every such case be governed and rate the tensile 
strain of iron in accordance with the lowest stamp found 
upon the same. 

"Rule 4 — The manner of inspecting and testing boiler 
plates, intended to be used in the construction of marine 



74 A TREATISE ON STEAM BOILERS. 

boilers, by the United States inspectors, shall be as follows, 
viz: 

" The inspector shall visit places where marine boilers 
are bein^ constructed, as often as' possible, for the purpose 
of ascertaining and making a record of the stamps upon the 
material, its thickness and other qualities. To ascertain 
the tensile strain of the plates, the inspector shall cause 
two pieces to be taken from each sheet to be tested, the 
area of one of which shall equal one-quarter of one square 
inch, the area of the other shall equal the square of its 
thickness, and the force at which these pieces can be parted 
in the direction of the liber or grain, represented in pounds 
avoirdupois — the former multiplied by four, the latter in 
proportion to the ratio of its area — that piece showing the 
greater tensile strain shall be held to be the tensile strength 
of the plate from which the test pieces were taken, and 
should the tensile strength ascertained by the test equal 
that marked on the plates from which the test pieces were 
taken, the said plates must be allowed to be used in the 
construction of marine boilers; provided, always, that the 
said plates possess the other qualities required by law, viz, 
homogeneousness, toughness and ability to withstand the 
eifect of repeated heating and cooling; but should these 
tests prove the marks on said plates to be overstamped, the 
lots from which the test plates were taken must be rejected 
as failing to have the strength stamped thereon. But noth- 
ing herein shall be so construed as to prevent the manu- 
facturers from restamping such iron at the lowest tensile 
strain indicated by the samples, provided such restamping 
is done previous to the use of the plates in the manufacture 
of marine boilers. 

" In the following table will be found the widths — 
expressed in hundredths of an inch — that will equal one- 
quarter of one square inch of section of the various thick- 
nesses of boiler plates. The signs + (plus) and — (minus) 



UNITED STATES GOVERNMENT TESTS. 



75 



indicate that the numbers against which these signs are 
placed are a trifle more or less, but will not in any instance 
exceed one-thousandth of an inch. 

" The gauge to be employed by inspectors'and others to 
determine the thickness of boiler plates and the widths in 
the table will be the Darling, Brown & Sharp's gauge, of 
Providence, Rhode Island, and will be furnished by the 
Treasury Department. This gauge has been approved by 
the Board of Supervising Inspectors : 



3^^ = 133- 
21 =119 — 
23 = 109 + 
Y' = 100 


.26 =96— .35 =71 

.29 =86— f^ = 67 

3^- = 80 ^^^ = 57 

.33 =76+ y^ = 50 






1 inch. 








v^ 








• • 








r\ 






1 inch. 
Figure 7. 





"All samples intended to be tested ontheRiehle testing 
machine must be prepared in form, according to the above 
diagram, viz, eight inches in length, two inches in width, 
cut out at their centers in the manner indicated. Two 
small center punch marks must be made on samples, one 
inch each side of their center, for the purpose of ascertain- 
ing their elongation or ductility. 

"In commencing a test, the person conducting the same 
must first apply weights to within four thousand pounds 
of one-quarter of the tensile strength marked upon the 
sample, and, after pumping the machine to equilibrium, 
apply the remaining weights at intervals of about fifteen 
seconds, until the sample is parted. 

" The smaller w^eights must be applied last, and should a 
sample part immediately on the application of such a 
weight, the weight last applied must be rejected. 



76 A TREATISE ON STEAM BOILERS. 

"The machine must be kept at equilibrium during the 
application of the weights, and, after the first application 
is made, the point where elongation commences must be 
ascertained by applying a pair of dividers to the center 
punch marks, at every additional weight, until the test is 
completed. 

''All tests made of boiler material must be recorded 
upon a table showing the following : 

" Date when tests were made. 

" From whom samples were obtained and by whom 
tested. 

" Material, iron or steel. 

" Stamp or label on samples, which must be the same as 
stamps on the material from which they are taken. 

" Thickness of samples, expressed in hundredths of an 
inch. 

" Width of samples, expressed in hundredths of an inch. 

•' Strain at which each sample parted. 

"Strain per square inch of section. 

'^Elongation of samples, expressed in hundredths of an 
inch. 

" Time consumed in tests, expressed in minutes and sec- 
onds. 

" Weight on machine at which elongation commenced. 

Elongation — In order to get anything like satisfactory 
results from any experiments made to determine the per- 
centage of elongation that any given sample of either iron 
or steel plates is capable of yielding, the samples ought to 
be at least six inches long, or better still, eight inches — the 
standard employed by the English and French governments. 
The samples should be rough polished on one side and 
ruled with lines at any convenient distance, say one-fourth 
inch apart. The elongation may easily be measured before 
or after breaking and the flow of metal observed at differ- 



TESTING BOILER PLATES. 77 

ent portions of the piece tested. The English Admiralty 
and Lloyd's Register both require that steel plates enter- 
ing into the construction of ships and boilers shall stand 
an elongation of twenty per cent in an eight inch speci- 
men. This would require an elongation of thirty-seven 
and a half per cent on a tAVO inch specimen, as deduced 
from the Lloyd's experiments See page 72. 

Iron boiler plate varies considerably, but will elongate 
from six to twenty per cent in samples of the same length 
as the above. 

Reduction of area — When wrought iron and steel sam- 
ples are broken to ascertain this tensile strength, the orig- 
inal area of cross section is always reduced and this 
reduction of area is a good index in determining the 
suitability of the material for boilers. When iron or steel 
plates are under high tension in a testing machine, the 
reduction of area will depend largely upon the inherent 
hardness or softness of the samples; thus, a soft fibrous 
iron will stretch and soon show a reduced area in which 
the fracture will occur. The amount of elongation and 
reduction of area will be found to be greater than if the 
iron had been of higher tensile strength. Hard specimens, 
either of iron or steel, stretch very little and in breaking 
do so suddenly with very little reduction of area. Soft 
steel elongates more than iron plates and will suffer a 
contraction amounting to from thirty to sixty per cent of 
original area. 

The writer was shown by Mr. Atkinson several sam- 
ples of "Sligo" iron, by Phillips, Nimick & Co., stamped 
fifty-seven thousand pounds and having an actual tensile 
strength of seventy-one thousand pounds, which showed 
after breaking an average contraction of area of thirty- 
five per cent. 



78 



A TREATISE ON STEAM BOILERS. 



Tenacity and ductility are so closely associated that 
separation is almost impossible, and the tendency of experts 
now is to require irons of a certain tensile strength to 
suffer a certain reduction of area before breaking, or when 
the elastic limit is reached. At a meeting of boiler plate 
manufacturers, held at Philadelphia, November, 1878, after 
^. very intelligent discussion of this subject, it was 

'^Resolved, That in the judgment of this meeting, plates should 
not' be used in a steamboat boiler that showed a contraction of area 
less than twelve per cent. We therefore recommend that all boiler 
plate, stamped with a tensile strain of under forty-five thousand 
pounds, should show contraction area of twelve per cent; forty-five 
thousand and under fifty thousand, should show fifteen percent ; fifty 
thousand and under fifty-five thousand, should show twenty-five per 
cent; fifty-five thousand and over should show 35 per cent." 

In some tests made by Mr. Kirkaldy, in 1876, upon 
Essen and Yorkshire plates, one hundred and twenty-eight 
specimens were tested, with results as follows — specimens 
ten inches long in central portion, by two inches in width : 

TABLE XXII. 





ESSEN. 


YORKSHIRE. 


Elastic stress 


25,144 pounds. 

48,028 pounds. 

74,542 pounds. 

83.8 per cent. 

1.94 per cent. 

7.76 per cent. 
22.70 per cent. 


27,477 pounds. 

45,515 pounds. 

56,875 pounds. 

18.6 per cent. 

0.85 per cent. 

6.41 per cent. 
14.80 per cent. 


Ultimate stress 


Stress for fractured area 


Contraction of area 


Extension at 30,000 pounds 


Extension at 40 000 pounds 


Extension ultimate 





TESTING BOILER PLATES. • 79 



Elasticity is that property which all bodies have in a 
greater or less degree and by which they retain their form 
when acted upon by any force which tends to distort their 
original figure. 

Elasticity is said to be perfect when a body acted upon 
by a force which distorts it will immediately and com- 
pletely recover its original form, when the force is removed. 

Elasticity is said to be imperfect when such a force per- 
manently alters or changes the shape of the figure either 
wholly or in part. 

The difiterent kinds of elasticity are known by names 
corresponding to the dififerent kinds of strains to which 
bodies can be subjected and are known under the several 
names — tension, compression, flexure and torsion. 

The elastic limit of any material represents the load 
which it is capable of receiving before it becomes perma- 
nently fixed or set, and from which it will not recover 
when the load is removed. Thus, there are limits to ten- 
sion, compression, flexure and torsion, beyond which the 
addition of a further application of weight or force will 
sooner or later lead to rupture. 

Reference is made, not to sudden changes in stress and 
shocks, but to gradually increasing strains. This defini- 
tion is theoretically worthless, for a limit so definite is not 
probable and much less is it proven.* Such investigators 
as Hodgkinson and Clark have observed that there are 
permanent changes of form under very small loads. At 
present we must be content with defining this limit with 
Fairbairn, as that stress below which the. changes in form 
are approximately proportioned to the forces, while above 
this they increase much more rapidly. 

All experiments, up to the present time, have shown 
that when the elastic limit is passed, the tensile resistance is 
considerably increased, while ductility and tenacity dimin- 

*Weyrauch. 



80 A TREATISE ON STEAM BOILERS. 

ish ; the metal becoming brittle and having little power of 
resistance to shock. In experiments at the Woolwich 
Arsenal, an iron rod, four times raptured by pull, gave the 
successive values of 3,520, 3,803, 3,978, 4,186. 

" It is found by experiment that, up to the limit of elas- 
ticity, the displacements suffered by the molecules of the 
body are sensibly proportional to the stress which causes 
them, so that a double displacement is caused by a double 
straining force; a triple displacement by a triple straining 
force; and so on."* 

The elastic limit is usually determined by weighing the 
force required to produce a perceptible and permanent 
change of form in the sample tested; this weight, divided 
by the area of the sample, gives the approximate elastic 
limit. 

The elastic limit of wrought iron is generally taken at 
one-half its tensile strength. Experiments made at Wash- 
ington on bars from five-eighths to two inches diameter 
show that for the particular grade of iron required for 
chain cables and for ship-building purposes generally, the 
elastic limit does not vary much from fifty-seven per cent 
of its tensile strength. 

Tests made of rivet steel from the Edgar Thompson 
steel works show, on three-quarter inch bars turned down 
to one-half inch^diameter, an elastic limit'of 41,000 pounds, 
the sample having 64,000 pounds tensile strength, with 
twenty-nine per cent elongation in a three inch specimen 
and fifty per cent reduction of area at point of fracture. 
The carbon in this steel was 0.11 per cent. 

For steel boiler plates from the same company having 
an area of .2282 (.62 X .36), the elastic limit was 37,634 
pounds, the tensile strength being 58,690 pounds. 

^Anderson. Strength of Materials, page 4. 



TESTING BOILER PLATES. 81 

Percussion tests are seldom resorted to, for the reason 
that very few irons will stand such a test. It is sometimes 
employed in testing plates for ship building, and in all 
such tests the superiority of steel over iron plates is 
clearly shown. Percussion tests have been made by allow- 
ing a ball weighing nearly thirty-four hundred pounds to 
fall on the unsupported middle of steel and iron boiler 
plates from distances varying from five feet six inches to 
twelve feet high. The first blow from a height of five feet 
six inches cracked the iron plate, and these cracks were 
much extended when the plate was turned up and struck 
on the other side from a height of eight feet. With steel 
boiler plates the first blow was from ^ve feet six inches 
high; this produced no flaw. The plate was then turned 
over ^nd struck from a height of eight feet six inches; it 
was then turned over again and struck from a height of 
ten feet; and was again turned over and struck from a 
height of twelve feet, and still no crack or flaw found 
in it. • 

« 

Bulging tests — These are seldom made, and so far as the 
writer is aware, are never required in any specifications for 
boiler plate. Experiments were made by Mr. Kirkaldy in 
1875 to ascertain the resistance of plates to and the effects 
under bulging stress, and are tabulated in his report on 
Essen and Yorkshire wrought iron plates. Fifty-four speci- 
mens, each twelve inches diameter, were pressed into an 
aperture ten inches in diameter, the "bulger" being five 
inches in diameter and having a rounded end turned to a 
radius of five inches. The stress was gradually increased 
until the specimen was pushed through the aperture or 
until the specimen gave way either by cracking or burst- 
ing. These experiments were made on plates having a 
nominal thickness of three-eighths, one-half and ^ve~ 

(7) 



82 



A TREATISE ON STEAM BOILERS. 



eighths of an inch. The three-eighths inch plates stood 
the test better than the latter, and are given in the follow- 
ing table taken from the report: 

TABLE XXTII. 

RESULTS OF EXPERIMENTS BY MR. KIRKALDY TO ASCERTAIN THE 

RESISTANCE TO BULGING STRESS OF WROUGHT IRON PLATES. 

NOMINAL THICKNESS THREE-EIGHTHS INCH. 

PLATES UNANNEALED. 



BKAND. 



Kriipp 

Krupp 

Krupp 

Mea 

Farnley 

Lowmoor .... 

Bowling 

Monkbridge 

Taylor's 

Cooper & Co 

Mea^ 



INCH. 

.44 

,44 

.44 

.44 

.42 
.38 
.40 
.37 
.39 
.38 
.39 



STRESS IN POUNDS BULGED, 
INCHES. 



0.81 
0.82 
0.82 

0,82 

0.77 
0.92 
0.74 
0.86 
0.80 
0.85 

0.83 



1.34 
1.35 
1.36 
1.35 
1.39 
1.54 
1.35 
1.47 
1.42 
1.47 

1.44 



1.75 
1.79 

1.80 

1.78 

1.85 
2.06 
1.78 
1.97 



2.12 
2.15 
2.16 

2.14 

2.32 
2.71 
2.46 
2.51 



2.58 
2.64 
2.67 

2.63 



ULTIMATE. 



O 
t^ 

K 

INCHBS. 

3.28 
3.28 
3.26 
3.27 
3.24 
3.20 
3.22 
2.75 
1.84 
1.65 

2.65 



POUNDS. 

139,940 
139,780 
137,560 

139,093 

116,810 
102,780 
114,4i0 
110,880 
54,720 
51,220 

'91,805 



Uncracked. 
Uncracked. 
Uncracked. 

Uncracked. 

Uncracked. 

Cracked. 

Burst. 

Burst. 

Burst. 



The English A^dmiralty tests for irons entering into the 
construction of steam boilers are as follows : 



TESTING BOILER PLATES. 



83 



TABLE XXIV. 

TENSILE STRENGTH REQUIRED OF WROUGHT IRON SUPPLIED THE ENG- 
LISH GOVERNMENT. 





HOW TKSTED. 


TENSILE STRAIN. 


CLASS OF IRON. 


IN TONS (2,240 
POUNDS) PER 
SQUARE INCH. 


IN POUNDS 

PER 

SQUARE INCH. 


BB or 1st class plate ii-on and 
sheet iron, 34 inch thick and 
above 


J With the grain 

1 Against the grain... 

j With the grain 

1 Against the grain... 

(with the grain 

1 Against the grain... 

- With the grain 

X AVith the grain 


22 
18 

21 
18 

20 
17 

22 
22 


49,280 
40,320 


BB or 1st class boiler plate iron 
^ inch thick and above 


47,040 
40,320 


B or 2d class plat^ or sheet iron.... 

Angle, Bulb, T, , , or other iron 

of ordinarv form 


44,800 
38,080 

49,280 


Best merchant iron, BB bar iron, 
y^, round, segmental. Fire bar 
iron 


49,280 







Forge tests are made by bending tbe samples of iron 
over a corner of a cast iron slab, of which the edge is 
slightly rounded. The plates to be tested may be either 
hot or cold, and are tested both with and across the grain. 
The test consists in determining the angle through which 
the plate will bend without showing signs of fracture. 
This, of course, depends upon both the quality of the iron 
and the thickness of the plate. 

The next table contains the requirements of the Eng- 
lish government in forge tests, and will be found to be 
well adapted for testing American, irons. The best Amer- 
ican irons will stand a severer test than that required of 
the BB 21 ton T. S. English iron. 



84 



A TREATISE ON STEAM BOILERS. 



TABLE XXV. 

SHOWING THE FORGE TESTS, BOTH HOT AND COLD, REQUIRED BY THE 
ENGLISH GOVERNMENT FOR PLATE AND SHEET IRONS. 





POSITION OF 

THE TxRAlN IN 

THE TEST. 


PLATE IRON. 


SHEET IRON 


KIND OF IRON 


— - 


COLD. 


HOT. 


COLD 




TESTED. 


THICKNESS. 


ALL 
THICK- 
NESSES 
UP TO 
1 INCH. 


HOT, 




I IN. 


i IN. 


1 IN. 


1 IN. 

15° 

5° 
10° 




T. S. 

Best Best, 21 tons. 
Best Best, 18 tons. 

Best, 20 tons 

Best, 17 tons 


Lengthwise.. 

Crosswise 

Lengthwise.. 
Crosswise 


70° 
30° 
55° 

20° 


35° 
15° 
30° 
10° 


25° 
10° 

20° 

5° 


125° 
90° 
90° 
60° 


90° 
40° 
75° 
30° 


125^* 
90^ 
90° 
60^ 



The angles given in the above table is that through 
v^hich the plate is bent, commencing at the horizontal, and 
is not the angle between the sides of the plate after it i^ 
bent. 

Mr. Kirkaldy^s experiments — The investigations of Mr, 
Kirkaldy, founded upon an elaborate series of experiments 
made by him on iron of every description and quality, led 
him to the following conclusions, among many others : 

" I. The breaking strain does not indicate the quality, 
as hitherto assumed. 

*'2. A high breaking strain may be due to the iron 
being of superior quality, dense, fine and moderately soft, 
or simply to its being very hard and unyielding. 

"3. Alow breaking strain maybe due to looseness 
and coarseness in the texture or to extreme softness, 
though very close and fine in quality. 



MR. kirkaldy's experiments 85 

"4. The contraction of area at fracture, previously 
overlooked, forms an essential element in estimating the 
quality of specimens. 

"5. The respective merits of various specimens can 
be correctly ascertained by comparing the breaking strain 
jointly with the contraction of area. 

" 6. Inferior qualities show a much greater variation 
in the breaking strain than superior. 

" 7. Greater differences exist between small and large 
bars in coarse than in fine varieties. 

•"8. The prevailing opinion of a rough bar being 
stronger than a turned one is erroneous. 

"9. Rolled bars are slightly hardened by being forged 
down. 

''10. The breaking strain and contraction of area of 
iron plates are greater in the direction in which they are 
rolled than in a transverse direction. (The experiments 
show the difference to be about ten per cent)." 



CHAPTER VI 



RIVETED JOINTS. 

Effects in Punching Plates — Experiments on Drilled and Punched 
Holes — Experiments on Ordinary and Spiral Punching — Strength 
of Riveted Joints — Single Riveted, Hand, Steam and Hydraulic 
Riveting — Double Riveted Lap Joints — Single and Double Riveted 
Butt Joints — Experiments on Thick Steel Plates by Punching and 
Drilling — Loss Due to Punching — Experiments on Chain and Zig- 
Zag Riveting — Testing Rivets — Testing Stay Bolts — Shearing Tests 
of Rivet Iron and Steel — Steel Rivets — Proportions for Single 
Riveted Lap Joints — Double Riveting — Calking. 

The only practical method of joining plates in the con- 
struction of boilers is by riveting. This is at best a very 
expensive and unsatisfactory way of making a joint, and 
the difficulties begin at the very outset by the loss of 
strength occasioned in punching the plates, and occurs by 
reason of, 

1. A reduction of area through tlie line of rivet holes, 
and 

2. By the disturbing influence of the punch on the 
remaining metal, still farther reducing its tensile strength. 

The bad effects of punching are, in general, more appar- 
ent in steel than in iron plates. It has been observed that 
when ordinary mild steel plates, having a tensile strength 
of upwards of seventy thousand pounds, have been tested 
after punching and before annealing, there is a loss of 
strength variously estimated from five to forty per cent of 
the original plate, depending somewhat on the hardness 
and the thickness of the plate. 



DRILLED AND PUNCHED HOLES, 



87 



The observed changes in the material in the line of 
punched holes are, increased hardness, alteration of struc- 
ture and loss of ductility. 

From, specimens tested, which had been cut from dif- 
ferent portions of the same plate and in the same line of 
punched holes, there does not appear to be a uniform dis- 
tribution of strain over the entire surface of the plate, but 
the disturbance of material is confined to within a very- 
short distance around the hole, extending from one to 
three-sixteenths of an inch. This inference is drawn from 
the fact that by drilling and reaming out punched holes 
and then testing the plate, making proper allowance for 
the reduced area, no perceptible decrease of strength is 
noted. 

TABLE XXVI. 

SHOWING RESULTS OF EXPERIMENTS MADE TO ASCERTAIN THE EFFECTS 

PRODUCED BY DRILLED HOLES AND BY PUNCHED HOLES 

UNDER PULLING STRESS, KRUPP'S WROUGHT- 

IRON. TESTS BY MR. KIRKALDY. 



Size of specimen — holes not de- 
ducted 

Size of specimen — gross area, 
square inches 

Ultimate stress per square inch... 

Ultimate stress — total 

Difference, or loss per square 
inch 

Difference or loss — per cent 

Elongation of holes — fractured... 

Elongation of holes — unfrac- 
tured 

Elongation of holes — total — inch. 



LENGTHWAY. 


CKOSSWAY. 


DRILLED. 


PUNCHED. 


DRILLED. 


PUNCHED. 


8 X .44 


8" X .44" 


8" X .44" 


8 X .44" 


3.52 


3.52 


3.52 


3.52 


33,005 lbs. 


28,006 lbs. 


30,053 lbs. 


24,329 lbs. 


116,180 lbs. 


98,580 lbs. 


105,790 lbs. 


85,640 Iba. 


19,590 lbs. 


26,534 lbs. 


20,142 lbs. 


26,101 lbs. 


37.2 


4S.6 


40.1 


51.7 


.34 inch. 


.17 inch. 


.27 inch. 


.15 inch. 


.18 inch. 


.05 inch. 


.13 inch. 


.03 inch. 


.52 


.22 


.40 


.18 



88 



A TREATISE ON STEAM BOILERS. 



TABLE XXVI— Continued. 





LENGTHWAY. 


CROSSWAY. 




DRILLED. 


PUNCHED. 


DRILLED. 


PUNCHED. 


Elongation of holes — total — per 
cent 


30.6 

Fibrous. 
52,595 K)s. 


13.0 
Fibrous. 

54,540 lbs. 


•23.5 
Fibrous. 

50,195 lbs. 


10.6 


Appearance of fracture 


Fibrous. 


Solid plate, ultimate sti-ess per 
square inch 


50,430 lbs. 





\ 




y 




• • 






• • 






• • 






• • 




r 




\ 



The drilled holes were made exactly the same size as those punched : Diameter 0.85 
inch X 4 holes = 3.40 inches, or 42.5 per cent of the width of the specimen. All the speci- 
mens were uuannealed. 

The engraving, fig- 
ure 8, represents thie 
shape of the specimens 
tested, being 8 inches 
Figure 8. in width of Central por- 

tion, with the rows of rivet holes two and a half inches 
apart between their centers; the pitch of the four holes 
across the plate being two inches, the one row being to 
exhibit the elongation of the holes after the plate was 
pulled asunder, the other to show the shape of the holes 
without being fractured. The punched holes were conical, 
as usual, being larger on the exit than on the entrance side 
of the plate. Those drilled were all made exactly to the 
smaller size, and thus suitable for the same sized rivet. 

It will be observed that in the first line of the table the 
space occupied by the rivet holes is not deducted as cus- 
tomary in making calculations on riveted joints, and that 
the gross and not the net area is stated. Mr. Kirkaldy's 
reason for doing so is, that it is better to give the total 
stress borne by the specimens of gross sectional area in 
pounds per square inch instead of the reduced area, so that 
any one can divide it by the net area, instead of the gross, 
area, should they prefer to do so. 



STRENGTH OF PUNCHED PLATES. 89 



The strength of the solid plate, or that without the 
holes, was taken from other tests of the sanne material, and 
is given in the last line of the table, in order to facilitate 
<3omparisons. The difference in strength between that of 
the solid plate and that with the holes represents the loss 
due to the latter. As already shown in the foot note to the 
table, 42.5 per cent of the plate was removed in forming 
the four holes. The actual loss appears as follows: In 
the plate with drilled holes 37.2 per cent loss wheu tested 
lengthway of the plate, and 40.1 per cent when tested 
^rossway; or a mean loss of 38.65 per cent for the two 
directions. In the plates with punched holes the loss, when 
tested lengthway of the plate, was 48.6 per cent and 51.7 
per cent when tested crossway of the plate, showing a mean, 
loss of 50.15 per cent for the tw^o directions. 

To summarize we have, then. 

Loss due to punching, mean 50.15 

Loss due to drilling, mean 40.01 

Showing a mean loss of 10.14 

per cent, due to punching over drilling. 

The ultimate stress borne by a specimen is greatly 
affected by the hardness or softness of the material and by 
the shape of the specimen. The softer the material the 
more rapidly does its sectional area become reduced by the 
specimen stretching and consequently in the amount 
of stress sustained. When the breadth of a specimen is 
reduced to a minimum atone point, a greater resistance is 
offered to its stretching than when formed parallel for 
some distance; and as the stretching is checked so will 
also the contraction of area, and with it will be an increase 
in the ultimate stress.* 

In all punched holes in boiler plates which the writer has 
measured, there Has been the same conical taper resulting 

* Kirkaldv. 



90 A TREATISE ON STEAM BOILERS. 



from the use of a die larger than the punch. This is the 
common method of fitting punches and dies for boiler 
work, originating, doubtless, in a necessity for a larger die 
because of a lateral motion of the punch, due to the imper- 
fect fitting of the slide to which the punch is secured. 
Then, afterwards, as punching machines were better built 
and had none of that lateral motion, the same practice of 
fitting punch and die continued, under the belief that it 
was necessary to good punching. The fact that some of 
the best examples of punching now on record was done in 
a machine in which the punch and die accurately fitted 
each other, shows that this matter of enlargement of the 
die may easily be overdone. 

The ordinary clearance for five-eighths and three- 
quarters inch dies is nearly ^-^ of an inch; the punch 
being made on size and the clearance allowed in the die. 

Cold punched nuts, as for example, those made by 
Hoopes & Townsend, Philadelphia, when taken as exam- 
ples of "commercial" punching as distinguished from 
experimental merely, are of considerable interest in this 
connection, owing to the entire absence of the conical 
holes spoken of in the preceding paragraph. It has 
already been shown in the table collated from Mr. Kirkal- 
dy's experiments, that there is a loss in punching iron 
plates over drilling, approximating ten per cent, Hoopes 
& Townsend have long been of the opinion that if properly 
performed, punching does not weaken good iron farther 
than by the simple reduction of area. In order to deter- 
mine the truth or falsity of this opinion they prepared 
^= \ ^ ^ a number of test 

^^- ^""^ J ^ ^i: : ^- ^ ^^^^^F^M T that represented in 



figure 9. These were 



Figure 9. made of bar iron 

IJ X f inch, and one of each pair had a hole f|- inch in 



STRENGTH OF PUNCHED IRON. 



91 



diameter drilled, and the other specimen the same sized 
hole punched in it. The specimens were then planed 
down next the hole, as represented in the engraving, so as 
to leave a thickness of three-eighths inch on each side of 
the hole. The other pairs had one-quarter, three-six- 
teenths and one-eighth inch respectively. These speci- 
mens were then broken by subjecting them to a tensile 
strain in one of Richie Brothers' testing machines, with 
the following results :* 

TABLE XVII. 

, STRENGTH OF PUNCHED AND DRILLED IRON BARS. HOOPES & 

TOWNSEND. 



THICKNESS OF 
BAR. 



f inch. 
f inch. 
I inch. 
f inch. 
I inch. 
f inch. 
f inch. 
4 inch. 



THICKNESS OUT- 
SIDE OF HOLE. 



_3_ 
16 



inch, 
inch, 
inch, 
inch, 
inch, 
inch, 
inch, 
inch. 



PUNCHED BAR 
BROKE AT 



31,710 
31,380 
18,820 
18,750 
14.590 
15,420 
10,670 
11,730 



pounds, 
pounds, 
pounds, 
pounds, 
pounds, 
pounds, 
pounds, 
pounds. 



DRILLED BAR 
BROKE AT 



28,000 
26,950 
18,000 
17,590 
13,230 
13,750 
9,320 
9,580 



pounds, 
pounds, 
pounds. 
pounds, 
pounds, 
pounds, 
pounds, 
pounds. 



From the engraving it will be seen that it was the por- 
tion of the iron immediately next to the hole, and which 
is usually supposed to be most affected by the action of 
punch or drill, which had to resist the strain. It will be 
seen that, in any case, the punched bars had the greatest 
strength, indicating that the punching had the effect of 
strengthening instead of weakening the iron. These 
experiments have given results just the reverse of similar 
experiments made on specimens of boiler plates; but 



* These tests were undertaken at the suggestion of and were first pnblished in the 
Railroad Gazette. 



92 



A TREATISE ON STEAM BOILERS. 



Messrs. Iloopes & Townsend argue that it is due, first, to 
the kind of material used, which is a tough and ductile 
iron, and second, to the method of punching. If a brittle 
and granular iron was used, the effect of the punching 
would be to crumble or disintegrate the iron in the imme- 
diate vicinity of the action of the punch; or if the punches 
and dies employed were so proportioned as to have a ten- 
dency to split open the bar, the metal around the hole 
would also be strained injuriously. But in manufacturing 
nuts they use a punch which fits accurately into the die, 
and the machines employed are heavy enough and made 
to work with sufficient accuracy so that the iron being 
punched is subjected to direct vertical pressure alone, with- 
out exerting any lateral or bursting strains in the iron. 
The efiect is, that the metal is compressed and thus made 
more dense and stronger. That some such action takes 
place seems probable from the appearance of the holes 
in the nut, which are straight and almost as smooth as 
though they were drilled. 



Kennedy^ s patent spiral shearing punch — A 
eleven-sixteenths inch punch, the size used in 
ordinary five-eighths inch riveting, is shown 
full size in figure 10. 

This punch derives its name from the fact 
that in its operation it performs its work in a 
circle, in the same manner that a shear does — 
in a straight line. Thus, to shear a hole two 
inches in diameter in a given plate of iron, is 
about the same as to shear ofi* a bar of iron of 
the same thickness, a little more than six inches 
in width. It is well known that to cut off a 
given plate of metal with the blades of the 
outter parallel, requires an amount of power and conse- 
quent strain upon the machine far beyond what it would 




Figure 10. 



SPIRAL AND FLAT PUNCHING. 9^ 

if the blades were only a few degrees angular to each other. 
This is just the difference between the flat and the "spiral 
shearing punch." 

It would seem a matter of some surprise, then, that 
with this knowledge, and in view of the enormous and 
growing extent to which iron and steel are used, that so 
little change, to say nothing of improvement, has been 
made in the punching of holes. Some few attempts have 
been made in that direction, which are too familiar to need 
special notice ; still, nothing has remained but the hard and 
costly and damaging method of the common flat punch. 
It is hard and expensive, because it not only requires 
a punching machine to be at least one-third heavier and 
stronger to meet the strain, but also requires at least fifty 
per cent more power to do the same work that can be done 
with the spiral punch. But the economy in power, the 
cost, and strain, and wear of machinery, which was the 
flrst object in the mind of the inventor, proves to be but a 
small part of the real value of the invention. 

So serious and well known is the injury and weakening 
of the surrounding parts after punching thick steel plates 
and sometimes iron plates, has led to a prejudice against 
punching at all where the strength of the material is of 
importance, and, therefore, resort has generally been had 
to the tedious and costly process of drilling. 

Experiments were 
made in steel plates cut 
to sample, as shown in 
figure 11, suitable for 
testing in a machine, , v^-i 

^ ^ 0.43 inch fhicK. 

with results as follows : figure u. 

Two holes were punched in each specimen, as seen in the 
cut, one with a flat punch and the other with a spiral 
punch. When tested, all the specimens broke through the 
hole punched with the flat punch. 



^ ! 


i J 


f i 


— ^ 



.7S| 


r 


A 



94 



A TREATISE ON STEAM BOILERS. 



In tests made to determine the relative amount of 
power required to operate the two kinds of punches, it was 
found that a seven-eighth inch "spiral punch" penetrated 
a five-eighth inch plate, at a pressure of twenty-two to 
twenty-five tons, while a seven-eighth "flat punch" in the 
same plate required thirty-three to thirty-five tons, thus 
showing a dead loss of ten tons of pressure on each hole, 
beside the additional strain and wear of machinery. 

The following table supplies some interesting data in 
regard to punched plates, as well as a comparison of the 
two punches: 

TABLE XXVril. 

RESULTS OF EXPERIMENTS MADE AT CREWE ON THE TENSILE STRENGTH 

OF SAMPLES OF THE SAME PLATE PUNCHED WITH KENNEDY'S 

SPIRAL AND ORDINARY PUNCHES RESPECTIVELY, 

BY MR. F. W. WEBB. 





BREAKING WEIGHT OF 
PLATE. 


ELONGATION. 


AREA OF 
PLATE 
UNDER 

TENSION. 




DIAME- 
TER 
OF HOLE. 


ACTUAL. 


PER SQUARE 
INCH. 


ON TWO 
INCHES 

OF 
LENGTH 


PER 
CENT. 


REMARKS. 








ACROSS 














HOLES. 










POUNDS. 


POUNDS. 










.885 


45,350 


63,752 


.11 


5.5 


.7114 




.885 


45,000 


60,318 


.23 


11.5 


.7461 




.895 


42,400 


57,495 


.]4 


7.0 


.7375 


1 


.89 
.89 


37,050 
42,800 


51,287 
60,692 


.03 
.06 


1.5 
3.0 


.7224 

,7052 


Punched with 
"ordinary" 
punch. 


.90 


45,150 


61,047 


.07 


3.5 


.7396 


1 


.895 


39,400 


55,465 


.09 


4.5 


.7032 




Mean 


42,393 


58,579 


.104 


5.2 


.7236 





STRENGTH OF RIVETED JOINT?. 



95 



TABLE XXVIII— CoNTiKUEij. 



BIAME- 

TER 

OF HOLE 



BREAKING WEIGHT OF 
PLATE. 



ACTUAL. 





POUNDS 


.885 


45,850 


.88 


48,000 


.88 


46,200 


.88 


44,250 


.88 


45,500 


.895 


47,600 


.885 


45,600 


Mean 


46,143 


.885 


40,350 


.89 


41,800 


.895 


44,350 


.885 


45,400 


.885 


42,100 


.89 


45,450 


.89 


34,300 


Mean 


41,9r)4 



ELONGATION. 



PER SQUARE 
INCH. 



POUNDS. 

63,285 
67,672 
63,584 
61,254 
64,148 
66,084 
61.476 

63,929 
55,693 
59,274 
63,073 
62,664 
58,109 
62,915 
47,480 

58,458 



ON TWO 




INCHES 




OF 


PER 


LENGTH 


CENT. 


ACROSS 




HOLES. 




.27 


13.5 


.25 


12 5 


23 


11.5 


.12 


6.0 


.26 


13.0 


.27 


13.5 


.09 


4.5 


.21 


10.6 


.21 


10 5 


.08 


4.0 


.24 


12.0 


.24 


12.0 


.24 


12.0 


.23 


11.5 


.07 


3.5 


.19 


9.3 



AREA OF 
PLATE 
UNDER 

TENSION. 



.7245 

.7093 

,7266 

.7224 

,7093 

.7203 

.7418 

.7220 

.7245 

.7052 

.7032 

.7245 

.7245 

.7224 

.7224 

.7181 



REMARKS. 



Punched with 
"Kennedy's 
spiral" punch. 



Punched with 
both punches. 
Fracture oc- 
curred in ev- 
ery case thro' 
the "ordina- 
ry" punch 
hole. 



Strength of riveted joints — The first reliable data on the 
strength of riveted joints was given by Sir William Fair- 
bairn in 1838, which was deduced from tests made with 
single and double riveted joints in plates of w^rought iron 
one-quarter inch thick. The relative values given by him 
were. 



96 



A TREATISE ON STEAM BOILERS. 



Tensile strength of the solid plate 100 

Tensile strength double riveted lap joint 70 

Tensile strength single riveted lap joint 56 

Since that time the percentages as given above have 
been in almost constant use by engineers and are still gen- 
erally accepted. As differences in material, kind and 
number of rivets, as well as varieties of arrangement and 
spacing of rivet holes became more common, tests were 
also made from time to time with more or less varying 
results, some of which are presented in this chapter. 

Mr. W. Bertram's experiments, as given by Mr. D. K. 
Clark in his Manual of Rules and Data, shows that for 
three thicknesses of specimens tested, viz, three-eighths, 
seven-sixteenths and one-half inch wrought iron plates, 
having a tensile strength of twenty tons (44,800 pounds) 
per square inch, that the averages of all the lap joints 
show that the three-eighths inch joint is the strongest, that 
the seven-sixteenth inch is nearly as strong, and that they 
are about one-quarter stronger than one-half inch lap joints, 
relatively to the thickness of the plate, thus: 



TABLE XXIX. 

COMPARATIVE STRENGTH OF RIVETED JOINTS. 



THICKNESS OF PLATKS. 



Strength of plate, per cent 

Strength of single riveted joint by hand.. 
Strength of double riveted joint by hand.. 



1 INCH. 


^« INCH. 


100 


100 


40 


50 


59 


70 



4 INCH. 



100 

60 

72 



The test specimens were each four inches wide and 
contained two rivets each, three-quarters of an inch diam- 
eter, placed two inches apart, center to center. Three tests 
of each were made and averages taken for the numerical 
value of percentages as given. 



RIVETED JOINTS. 97 



The figures in the above table show that for single or 
double riveted joints, thin plates are to be preferred to 
thick ones. 

Experiments by David Greig and Max Eyth^ Leeds ^ 
England — In some tests of riveted joints made by these 
gentlemen (1879), in which each construction of joint 
was represented by four specimens of exactly the same 
dimensions, two being of steel and two of iron, one 
specimen of each material was of Brown's and one of 
CammelFs make. This distinction was made, not for the 
purpose of testing two different materials, but to get a 
fair average result. Tests of these two materials, made 
on samples two inches wide by three-eighths inch thick, 
gave an average breaking strain per square inch of solid 
plate as follows : 

TOXS, POUNDS. 

Cammell's iron 21.9 49,056 

Cammell's steel 24.0 53,760 

Brown's iron 22.6 50,624 

Brown's steel 27.6 61,824 

This gives. 

Average of iron 22.25 49,840 

Average of steel 25.80 57,792 

The iron specimens were invariably riveted together 
with iron rivets, the steel with steel rivets. The thickness 
of all plates was nominally three-eighths inch ; the rivets, 
except in four cases, were nominally five-eighths inch, the 
holes being drilled eleven-sixteenths inch in diameter. 
The slight difference in the thickness of the plates was 
reduced by calculation in working out the experiments 
to a uniform thickness of three-eighths inch. 

Test pieces were prepared, as shown in table XXX, 
to determine the relative value of punching and drilling. 
All the specimens were alike in their dimensions, two 

(8) 



98 



A TREATISE ON STEAM BOILERS. 



pieces, six and a half inches wide, forming a single riveted 
lap joint, with four, five-eighths inch rivets, one and five- 
eighths inch pitch. The punched and drilled holes were 
of the same diameter, viz, ^ inch. The die for the punch 
was 1^ inch diameter, or the usual -^ inch clearance. 
The conical hole produced hy punching measured at the 
top 0.708 inch and at the bottom 0.790 inch, there being 
no measurable difference between iron and steel in this 
respect. Four of these specimens were of iron, two being 
drilled and two. punched, all steam riveted. In the 
punched specimens the conical holes were placed with 
their smaller ends in contact. Of the two drilled speci- 
mens, one broke through the plate, the other sheared in 
rivets. The average strength of the same proved to be 
50.4 per cent of the strength of the solid plate. 



TABLE XXX. 

STRENGTH OF LAP JOINTS, SINGLE RIVETED. 



v_ 




J 




; • 






; • 






; • 






: • 




/""""" 


P'IGURE 


^ 




12. 



PLATE SIX AND ONE-HALF INCHES WIDE, THREB-EIGHTHS INCHES THICK, FOUR 
FIVE-EIGHTHS RIVETS, ONE AND FIVE-EIGHTHS INCH PITCH. 

Greig and- Myth. 



DESCRIPTION OF 
SPECIMEN. 


AVERAGE BREAKING 

STRAIN OF SPECIMEN 

IN POUNDS. 


BREAKING STRAIN OF 

SOLID PLATE PER 

INCH OF AVIDTH, IN 

POUNDS. 


BREAKING STRAIN OF 

SPECIMEN PER INCH 

OF WIDTH, IN POUNDS. 


STRENGTH OF SEAM 

PER CENT OF SOLID 

PLATE. 


> . 
« Q 

05 
H 

03 


SHEARING RESISTANCE 
OF RIVET IRON PER 
RIVET, IN POUNDS. 


STRENGTH OF SPECI- 
MEN, PER CENT OF 
NORMAL STRENGTH 
OF MATERIAL. 


Iron plate, drilled holes 

Iron plate, punched holes.. 


61,350 
49,400 


18,700 
18,700 


9,438 
7,600 


50.4 
40.6 


16,325 


15,810 


PLATES 

84.1 
75.5 


KIVBTS. 

103 











RIVETED JOINTS. 



99 



TABLE XXX— Continued. 



DESCRIPTION OF 
SPECIMEN. 


AVERAGE BREAKING 

STRAIN OP SPECIMEN 

IN POUNDS. 


BREAKING STRAIN OF 

SOLID PLATE PER 

INCH OF WIDTH, IN 

POUNDS. 


Eh W 

O S C 

^^ "^ 

5 Z P 

sag 

< u -> 

aw^ 

p; 03 E^ 

w o 
12,300 
12,950 
13,060 


STRENGTH OF SEAM 

PER CENT OF SOLID 

PLATE. 


a 
> . 

aP 

< '^ 
« 


SHEARING RESISTANCE 
OF RIVET IRON PER 
RIVET, IN POUNDS. 


STRENGTH OP SPECI- 
MEN, PER CENT OF 
NORMAL STRENGTH 
OF MATERIAL. 


Steel plate, drilled holes 

8teel plate, punched holes 
and annealed 


• 
79,800 

, 84,700 

84,900 


21,700 
21,700 
21,700 


50.6 
59.6 

60.2 


19,950 
21,175 
21,225 


18,440 
18^440 
18,440 


PLATES 


RIVETS. 

108 




115 


^Steel plate, punched holes 
and unannealed 




115 









Second Series of Tests for Different Modes of Riveting. 



DESCRIPTION OF 
SPECIMEN. 



Iron, hand riveted 

lrf)n, steam riveted 

Iron, hydraulic riveted. 

Steel, hand riveted 

Steel, steam riveted 

Steel, hydraulic riveted 





IN OF 
PER 

H, IN 


IN OF 
INCH 
)UNDS 


% 


a 
> . 


TANCE 

PER 
UDS. 


BKEA 
SPEC 

UNDS 


X«CW 
H H ►- Q 


STRA 
PER 
IN PC 


o ^ a 
o o P 




^ESIS 
IRON 
PON 


fa o 


z'^feo 


gaa* 


£ f- 5 

^ 2 S^ 


^2 


S '- 


< 2 2 
Pi S - 


5 o p^ 


S 1 H 


w ^ 
2 (J 

a 


2z 


^>^H- 
M IH H 

p^ p:; a 


a <: 


^ o u 


w £d 5 


£ a; 


» 


< r > 


> « 


S to 2 




H a 


H 


a a M 


56,550 
61,850 


n 


s-§ 


<A Ph 


w 


5 O Pi 


18 700 


8,700. 
9,515 


46.5 






18,700 


50.9 


16,775 


15,810 


64,350 


18.700 


9,900 


53.9 


16,875 


15,810 


69,800 


21,700 


10,730 


49.4 


17,450 


18,440 


82,600 


21,700 


12,707 


58.5 


20,650 


18,440 


76,700 


21,700 


11,800 


54.4 


19,175 


18,440 



I 

Ph H 
w 2 



a 

H 
2^ 

a ;2 

a; K 

H a 

to (i 



2 Pi 
K a o 



PLATES 

82.5 



84.6 
89.6 



106 
107 
94.9 
112 
107 



The practical conclusions to be drawn from the above 
table are, that the tensile strength of iron plates, single 
rivQted, range from 40.6 to 53.9 per cent, and for steel from 
49.4 to 60.2 per cent. 



100 \ ' A TREATISE ON STEAM BOILERS. 

In the experiments the hand riveted iron specimens 
broke through the plate, showing the seam to have a 
strength of 46.5 per cent of the solid plate, and the iron 
section to break v^ith 82.5 per cent of its normal breaking 
strain. Of the iron specimens riveted by hydraulic and 
steam powder, one broke in the plate and the other sheared 
the rivet in each case. The strength of the seam proved 
to be 50.9 per cent of the solid plate for steam, 53.9 per 
cent for hydraulic pressure ; the breaking strain of the iron 
being for steam 84.6 per cent and for hydraulic pressure 
89.6 per cent of its normal breaking strain. Here, then, 
hydraulic riveting has come out distinctly superior to steam 
riveting, its quiet action no doubt injuring the material 
less than the shock given by the steam riveter. Hand 
riveting, of course, is left far behind by the tw^o other 
methods. 

In regard to the tests on steel plates, all the specimens 
(six) broke by the shearing of the rivets. Hand, steam and 
hydraulic pressure gave respectively 49.4, 58.5, 54.4 per 
cent for the strength of seam as compared v^ith the solid 
plates, and the rivets broke respectively w^ith 94.9, 112 and 
107 per cent of their normal shearing strain. Here, then, 
hydraulic riveting has come out second best, the proportion 
corresponding remarkably vrell w^ith previous experiments 
concerning a single rivet. The fact then seems to be that 
the plate, especially if soft, is much less injured by hydraulic 
riveting, and that this method has, therefore, a decided 
advantage where the plate is the weaker part, but that 
the rivet itself is stronger w^hen put in by the steam riveter 
(at least by the machines used for these experiments), 
owing, probably, to the greater compactness of the rivet 
material obtained by the sudden shock. 



RIVETED JOINTS. 



^ 101 



TABLE XXXI. 

STRENGTH OF LAP JOINTS— DOUBLE RIVETED PLATE, SEVEN AND A HALF 
INCHES WIDE, THREE-EIGHTHS INCH THICK. 



X. 



y 



r 



X 



Figure 13. 
Greig and Eyth 



DESCRIPTION OF 
SPECIMEN. 



Iron plate, six % rivets 
(flat zigzag) 

Steel plate, six % rivets 
(flat zigzag) 

SECOND SERIES. 

Iron plate, eight % rivets 
(sharp zigzag) 

Steel plate, eight % rivets 
(sharp zigzag) 



e 125 

^ w 

<! Jz; » 

B5 2 '-' 



90,700 



113,300 



83,100 



102,460 



"05 S 

:5 (^ w 

P5 W g w 

H H S 

"^ It" P 

'-' r^ O Pk 
^ Q 

•< 2 >^ 

ago 

a: w K 



18,700 



21,700 



18,700 



21,700 



PM U4 "> 

<! "1 O 
K « fi< 

f-' ? !?- 
w f^ ^ 

a izi '^'- 
(z; « a 

sag 

<! O t) 

El) a ^ 

fO « fe 

o 



12,093 
15,107 



11,086 



13,661 



< l-< 

M O 
W 

a 

o ^ w 

p g Ph 

a 

H a 

M (1< 



64.6 



70.0 



59.2 



62.9 



a 

M Q 

a 'A 

a P 

fe o 

H 



15,733 



18,883 



a 

>. a M 
!^ ^ Q 
H t, izi 
2o5 



ss2 

o w " 

W S W 
■< t. !=^ 

M « M 

»*'(-. r^ 



1 tt 

M a -^ 

"^ o S 

a ® 

Oh B^ . 

"» !^ 9 j 

..^ a w 3 

So H^ 



O - CO pj 

i Hi a 



O « 



w 



15,810 



18,440 



S a o a 



PLA TES RIVKT8 



113 



104 



114 



99.4 



102. 



Iron plates have iron rivets ; steel plates steel rivets. 



These tests show a reduction in strength of seam by 
increasing the number of rivets in a seven and a half inch 
plate, from six to eight, and also their diameters from five- 
eighths to three-quarters inch. The plate containing the 
six rivets, five-eighths inch diameter, had two and a half 
inch centers of rivets lengthwise of the seam, the second 
row of rivets being in a line one inch distant, making the 
diagonal centers of rivets one and five-eighths inches. 



102 A TREATISE ON STEAM BOILERS. 

One of the iron specimens broke through the plates, the 
fracture following a zigzag line through the rivet holes ; 
the other sheared the rivets. The strength of the seam 
was 64.6 per cent the full strength of the plate. In the 
first case (zigzag fracture), the section of the plate along 
the line of fracture broke with 113 per cent of its normal 
tearing strain. The steel samples broke through the 
rivets, the latter showing a shearing resistance only two 
per cent above the normal. This reduction of strength, 
as compared with former test pieces, is caused by tlie 
absence of bending of the joint, owing to the double row 
of rivets keeping the plates more rigidly in line. The 
strength of the seam was the highest obtained, being 70 
per cent of the solid plate. 

In the second series of tests in table XXXI, the test 
specimens were of the same dimensions as the first, viz, 
seven and a half inches wide, three-eighths inch thick, the 
number of rivets being increased to eight and their diam- 
eters to three-quarters of an inch. The pitch of these rivets 
was one and seven-eighths inch lengthwise of the seam, 
and one and seven-eighths inch centers of rivets to the 
second row, or equidistant in any direction. Although 
the joint is very rigid, it is rather weak in the plate against 
direct tensile strain and was sure to break in a straight 
line across the rivets. Its strength proved to be 59.2 of 
the solid plate for iron and 62.9 per cent for the steel 
specimens, showing again the great advantage gained by 
the effect of a double row of rivets in preventing the 
bending of the joints under stress. 



RIVETED JOINTS. 



103 



TABLE XXXII. 

STRENGTH OF BUTT JOINTS, SINGLE AND DOUBLE RIVETED, SINGLE AND 

TWO COVERS, IRON AND STEEL PLATES, THREE-EIGHTHS 

INCH THICK, RIVETS FIVE-EIGHTHS OF 

AN INCH IN DIAMETER. 



"V 



r 



Figure 14. 



X 



■\. 



DKSCRIPTION OF 
SPECIAIEN. 



Iron plate, GJ^ inches wide, 
single cover, single riv- 
eted, four % inch riv- 
ets in each plate. Fig- 
ure 14.. 



Steel plate, 63^ inches wide, 
single cover, single riv- 
eted, four % inch riv- 
ets in each plate. Fig- 
ure 14 



Iron plate, 7)^ inches wide, 
single cover, double 
riveted, six % rivets in 
each plate. Figure 15... 

Steel plate, IY2, inches wide, 
single cover, double 
riveted, six y^ rivets in 
each plate. Figure 15... 



^r 



j^ 



__ 



A. 



Figure 15. 
Greig and Eyth. 



o 2; 

^ 'A 

w e . 

< U tn 

a a Q 

■< !5 !zi 

03 5 '-I 



58,000 



78,800 



78,000 



110,750 



O 03 S 

!^ ? - 

« P. a 

05 W S w 

H r; y Q 

M <J !^ ^ 

z *^ ^ o 

S Q o 0- 

<! J W 

a o o 

05 «2g 

pq 



18,700 



21,701) 



18,700 



21,700 



o W Q 

sgg 

< o 

oj 05 a< 

M Ol ^ 
^ ^ w 

y 2 Q 
<- O ;-« 

05 ^ 

3 M fe 
o 



8,928 



12,123 



10,400 



14,76G 



a ij 

05 O 

W H <! 

H 2:; a 

o a f^ 

iz; o 

a 03 

05 a 



4f).6 



55.8 



55.6 



68.0 



05 
H 

9!) 



19,700 



18,346 



a 

s? r^ M 

H *" ^ 

S 5^ ^ 

M o o 

a 05 o< 

03 ^ ^ 

cs a „ 

a > &. 

>-j i-i a 

05 03 r 

;1 fe ^ 



18,440 



18,440 



Si 


S 




a 


H 




Oh u. 


<i> 


^ 


03 H 


•a 




^ i^ 


a 




&j an 


05 


0: 





H 


a 


W oi 


« H 


H a 




S 


CS Ph 


■< 


»5 ►, ^ 
H !2i 05 




ftj a 




H g !z; 




w 







PLATES BIVBTS 



82.3 



103 



107 



104 



104 



A TREATISE ON STEAM BOILERS. 



TABLE XXXII— Continued. 



DIMENSIONS OF 
SPECIMKN. 



Iron plate, 6)^ inches wide, 
two covers, single riv- 
eted, four Ys inch riv- 
ets in each plate, Fig- 
ure 14 



Steel plate, 63^ inches wide, 
two covers, single riv- 
eted, four % inch riv- 
ets in each plate. Fig- 
ure 14 

Iron plate, 1%, inches wide, 
two covers, double riv- 
eted, six % inch rivets 
in each plate. Figure 
15 

Steel i>late, 73^ inches wide, 
two covers, double riv- 
eted, six 5^ inch rivets 
in each plate. Figure 
15 



c5>^ 


^« 


R s 


w s . 


< H M 


w « ft 




., fe o 


Bo^ 


<;z;i2i 


M >i '-' 


H < 




76,850 


95,150 


89,150 


110,500 



O K 

H 



"" hi 
!<5 



S ft 
M O O 



>1 ft 
^§ 

fe o 
O fc 



18,700 



21,700 



18,70n 



21,700 






fe fc 






11,746 



13,100 



n,8S6 



14,740 



W B < 

H g 1-! 

O g fe 

H W 

CO PL, 



62.7 



60.4 



6.3.5 



68.0 



;2; « S 

^ II, ft 

^ ^ 5 

in !z; s 

H £ 6- 

« 3 « 

<! ;> 

W fe 3 

K o K 



<^ H S ►J 

1^ H M pj 

o u ;; H 

ffi « "* ^ 

55 Ph <! « 






tf O 
O 



PLATES RIVETS 



108 



111 



118 



126 



Iron plates have iron rivets, steel plates steel rivets. 

Figure 14 is a representation of the two test specimens 
given in the iirst two lines in the table, being single riveted 
butt joints, with a cover plate on one side only, the four 

five-eighths inch rivets being 

arranged exactly as in the lap 

joints given in table XXX. The 

Figure 16. rcsult was Unfavorable. The 

cover (which was of the same strength as the plate) bent 

readily, as shown in figure 16. 




RIVETED JOINTS. 105 



The iron specimens gave way in the plate, the seam 
showing a strength of 46.6 per cent of the solid plate ; that 
is to say, not higher than the ordinary lap joints. The 
steel samples sheared through the rivets, their strength 
being 55.8 per cent of the solid plate. Experiments made 
on plates seven and a half inches wide, with a single cover 
and double riveted, the arrangement of the rivets being the 
same as the double riveted lap joints already described, 
the iron specimens gave even less favorable results than 
the corresponding lap joints, proving conclusively that a 
butt joint of the ordinary description, viz, with one cover 
of the same thickness as the plate, has scarcely any advan- 
tage over the ordinary lap joint. The results are very 
different in butt joints with double covers, of which eight 
samples were prepared, four being single riveted and four 
double riveted. The shearing resistance of the rivets is 
by this construction at once doubled, as the two sections 
have to be sheared to break a rivet. All specimens, there- 
fore, broke through the plates. But the tensile resistance 
of the plates was also greatly increased, partly because the 
construction prevents all bending of the plates, partly 
because a considerable amount of frictional resistance 
between the plates is gained. Thus, in all these cases, 
though the plates broke, the strength of the seam was from 
60 to 68 per cent of the strength of the solid plate, and the 
breaking strain of the fractured section rose in the last case 
to 126 per cent of the normal breaking strain of the steel. 

From what has already been said it appears that, for 
three-eighths inch iron plates the difference between 
punched and drilled holes is about ten per cent in favor of 
the latter, as compared with the strength of solid plate. 
For steel the difference between drilled and punched holes 
in unannealed plates is about four per cent in favor of 
drilling, and three per cent if the plates are annealed after 
punching. A difference so slight as this would hardly 



106 A TREATISE ON STEAM BOILERS. 

"pay" on the one hand for the expense of drilling, nor on 
the other for the expense of annealing; if plates are pro- 
perly annealed at the manufactory there ought to be no 
further necessity for annealing in ordinary boiler construc- 
tion in which one-quarter, five-sixteenths and three- 
eighths inch steel plates are used, having a tensile strength 
of sixty to sixty-five thousand pounds, and will stand the 
bending and temper tests already described. 

Mr. Boyd's experiments on thick steel plates — The effect of 
punching thick plates is different from what has been 
described in the pages immediately preceding, as fully 
shown in the abstract of results obtained by Mr. William 
Boyd, Newcastle-on-Tyne, England. In fourteen samples 
of steel boiler plates tested by Mr. Boyd, the average ten- 
sile strength was found to be 28.7 tons (64,288 pounds) per 
* square inch, and with one exception exhibited a remarkable 
uniformity, showing that regularity of quality is now 
obtainable in a large specification of steel plates, without 
practical difficulty. 

Elasticity is lost at an early point, viz, at an average of 
16.6 tons (37,184 pounds) per square inch, equal to 58 per 
cent of the ultimate breaking strain. Elasticity also com- 
mences early, for it was quite perceptible when the speci- 
men tested had a strain of but eleven tons (24,640 pounds) 
per square inch of section. 

In endeavoring to .arrive at a fair estimate of the 
amount of stretch in relation to the length, it was thought 
best to eliminate all the short specimens as not affording 
reliable data. Taking four specimens six and a half inches 
long, three specimens seven and a quarter inches long and 
two specimens twelve inches long, the ultimate stretch or 
elongation was found to be 26.5 per cent of the length of 
the specimen. 



PUNCHING AND DRILLING THICK STEEL PLATE. 



lOT 



TABLE XXXIII. 

EXPERIMENTS ON PUNCHED AND DRILLED HOLES IN THICK STEEL 
BOILER PLATES, BY WILLIAM BOYD. 






"u 
4) 



DESCRIPTION. 



Steel, punched holes 

Steel, punched holes 

Steel, drilled holes 

Steel, punched holes 

Steel, punched holes 

Steel, punched, annealed 
Steel, punched, annealed 
Steel, drilled holes 





< 






1^ 




KI 




02 






P3 


b 


"/U 


o> 




■< 


o 


o 


02 


SIZE. 


1-3 
< 

O 


1 H 




03 . 

H 02 

02 ? 




H 


<J 


i^ 


H 




O 


HH 


O 


PS 




Ed 


Q 


D3 


H 




M 


li 


P3 

75 


M 


Ss^tXH 


3.98 


18.8 


8^Xii 


398 


u 


70 


17.4 


"32/\16 


4.01 


1 3 


110 


27.4 


8 XH 


4.72 


1^ 


103 


21.8 


8 XH 


4.72 


1-^ 


97 


20.5 


mxn 


4.70 


1 3 


142 


30.2 


8 XH 


4.72 


1 3 
^3^ 


136 


28:81 


8 XH 


4.72 


1 3 


146 


30.9 






[■18.1 



^21.15 



29.5 



The first two specimens in the first series were punched 
holes, and show a mean breaking strain of 18.1 tons (40,544 
pounds) per square inch ; taking twenty-eight tons (62,720 
pounds) as the breaking strain of solid steel plate, this 
shows a loss of strength equal to 35.36 per cent. In the 
last experiment of the first series, the holes were drilled, 
and the specimen broke at 27.4 tons per square inch, show- 
ing a loss of only 2.15 per cent. 

Mr. Boyd next desired to ascertain whether the process 
of heating or annealing the plates in the furnace had any 
eflect; for, in practice, all the shell plates of this thickness 
were so treated, being put into a plate furnace and heated 
to a dull red heat before being bent in the rolls to the 
required diameter. The second series in the table exhibits 
the results of these experiments. In the first two speci- 
mens the holes were punched and broke at a mean strain 
of 21.15 tons (47,376 pounds) per square inch. In the 



108 A TREATISE ON STEAM BOILERS. 

second pair, the holes were also punched, but the specimens 
were afterward annealed in the manner described, and the 
mean breaking strain rose to 29.5 tons (66,080 pounds) per 
square inch, showing a result fully equal to that allowed 
per square inch for solid plate. In the fifth plate the holes 
were drilled, and the breaking strain was 30.9 tons (69,216 
pounds) per square inch. If, then, the mean breaking 
strain of these last three specimens be taken at 30.2 tons 
(67,648 pounds) per square inch, and the breaking strain of 
the first two specimens with punched holes as 21.15 tons 
(47,378 pounds) per square inch, a loss of 29.97 per cent is 
shown in this plate (all the ^ye samples being cut out of 
one plate, as being due to the operation of punching the 
holes. 

The results of Mr. Boyd's experiments on thick plates 
seem to show, 

1. *' That steel is not injured by drilling. 

2. '' That it is injured to the extent of about 33 per cent 
by punching ; but, 

3. " That the nature of the material is restored entirely, 
if the plate be heated and annealed after punching and 
allowed gradually to cool out. 

In describing the effects consequent on punching holes 
in steel plates for use in boiler making and for other simi- 
lar purposes, and comparing their strength and adaptability 
with plates having drilled holes, it becomes a matter of the 
highest importance to notice the quality of the steel sub- 
mitted to each of these processes. The highly carbonized 
plate, or one that is characterized by hardness and density 
of substance, reveals in its fracture a very fine, bright, 
granular appearance. This, when closely inspected, is 
found to contain a well arranged and well developed mass 
of particles, each of which, by the laws of cohesion and 
affinity, will closely adhere to its fellow, and being so highly 
carbonized and pure, will offer immense resistance and 



CHAIN AND ZIGZAG RIVETING. 



109 



power all the time there is not a leading fracture in any 
part of the plate. But the exceeding hardness of the par- 
ticles prevents what is most desirable in a plate subjected 
to varied strains and fitful action, namely, a certain amount 
of elasticity, combined with capability of elongation. Thus, 
while the more inferior particles of a common plate, under 
heavy strains, have a tendency to overlap each other and 
blend together, the reverse is the case with the hard plate, 
the particles of which, refusing to elongate and overlap 
each other, continue to hold intact their more perfect forms 
till they suddenly part. This is evident in the process of 
punching, for the pressure of the punch and die on the 
metal disturbs and disarranges the particles in the imme- 
diate locality of the hole and creates internal — though 
imperceptible — fractures. 

The writer is of the opinion, from the results of 
experiments made on one-quarter and five- sixteenths 
steel boiler plates, below seventy thousand pounds, 
that the loss by punching does not aflect the strength of 
the plate sufficiently to warrant the extra trouble and 
expense of annealing, especially if the die is somewhat 
larger than the punch, so that the hole shall be slightly 
conical. The heat from the hot rivet will then sufficiently 
anneal the plate. 

Experiments by Mr. Boyd on chain and zigzag riveting — 
In order to ascertain experimentally whether there was an 
important difference in strength between chain and zigzag 
riveting, Mr. Boyd had test specimens of each, prepared 
similar to figures 17 and 18. 



V 




y 




•; • 






• '.• ^ 






•; • 






• -.'•-. 






r •' • 






* !• 




^ 




N 



Figure 17. Zigzag Riveting. 



110 



A TREATISE ON STEAM BOILERS. 



V 






• O 



y 



-/ N- 

FiGUKE 18. Chain Riveting. 



Both test specimens were cut from a steel boiler plate, 
eleven-sixteenths of an inch thick. The following table 
gives the particulars of the test: 

TABLE XXXIV. 

EXPERIMENTS MADE ON STEEL BOILER PLATES TO DETERMINE THE 
RELATIVE TENSILE STRENGTH OF CHAIN AND ZIGZAG 
RIVITED JOINTS, ARRANGED FROM DATA FUR- 
NISHED BY MR. BOYD. 



Width of test specimen.... 

Thickness of test specimen 

Thickness of side plates (one on each side), 

Length of side plate 

Kivets, diameter 

Rivets, spacing C to C across the specimen. 

Rivets, spacing C to C of rows 

Area of solid plate 

Net sectional area of plate through rivet 
holes 

Percentage of net to original area 

RESULTS. 

Total strain at which specimens broke 



STYLE OF RIVETING. 



CHAIN. 


ZIGZAG. 


12 inches. 


12 inches. 


^inch. 


11 inch. 


\ inch. 


\ inch. 


11^^ inches. 


10 inches.- 


li|3g^inch. 


\^^ inch. 


4 inch. 


4 inches. 


2f inches. 


2 inches. 


8^ inches. 


8^ inches. 


6.057 inches. 


6.057 inches. 


73,41 per ct. 


73.41 per ct. 


f 174 tons, 
1 389,760 R)s. 


( 140 tons, 
1 313,600 lbs. 



CHAIN AND ZIGZAG RIVETING. 



Ill 



TABLE XXXIV— Continued. 



Excess of strength in the chain riveting... 

Relative strength of joint and solid plate, 
at 26 tons (58,240 lbs.) per square inch. 

Relative strength of joint and solid plate, 
at 28 tons (62,720 lbs.) per square inch, 



STYLE OF RIVETING 



CHAIN. 



r 34 tons, 
I 76,160 lbs. 

SI. 11 perct; 



75.32 per ct. 



ZIGZA(;. 



65.32 per ct. 



60.66 per ct. 



It will be observed that the chain riveted joint is 24.28 
per cent stronger than the zigzag riveting, which raises 
the interesting question whether it is not to be preferred, 
even though the area of solid plate left untouched by rivet 
holes remains the same. 

There has long been a misconception as to the 
real strength of chain " riveted over single riveted 
joints, and an opinion has obtained in the minds of 
.many engineers that a chain joint, similar to that shown 
in figure 18, is no stronger than the single riveted joint, as 
in figure 14, the argument being that the maximum strength 
of the seam must be that of the weakest section, and, 
hence, through the line of rivet holes ; it being either denied 
or doubted that by simply extending th.e plate and inserts 
ing a second row of rivets should add to the strength of 
the first row, nor to the strength of the joint, and- that when 
a sufiicient strain is brought to bear upon the joint, it would 
be quite as likely to break through the first row of rivet 
holes as though the second row were not there. This notion 
in regard to chain joints is entirel}^ disproved by what has 
already been shown in Mr. Boyd's experiments, and by 
results taken from those of Mr. Bertram, and given in 
table XXXY. 



112 



A TREATISE ON STEAM BOILERS. 



TABLE XXXV. 

SHOWING THE COMPARATIVE STRENGTH OF SINGLE RIVETED AND DOUBLE 
CHAIN RIVETED JOINTS ON WROUGHT IRON BOILER PLATES OF DIF- 
FERENT THICKNESSES, EACH HAVING AN AVERAGE TENSILE 
STRENGTH OF TWENTY TONS (44,800 POUNDS) PER SQUARE INCH. FROM 
EXPERIMENTS BY MR. BERTRAM. 





V 








y 1 




• 
• 
• 


• 
• 
• 
• 




r 


Figure 19. 


> ! 








»» 


V 


y 




• • 


• • 








• • 


1* • 








• • 


;• • 




( 








X 



Figure 20. 





NET 


ULTIMATE STRENGTH OF 


JOINT. 


DESCRIPTION OF JOINT. 


\ INCH 
PLATES. 


/^ INCH 
PLATES. 


1 INCH. 
PLATES. 


AVERAGE 

FOR THE 

THREE 

PLATES. 


Entire plate 


PER CENT. 
100 

40 

40 

59 


PER CENT. 
100 

50 

54 
70 


PER CENT. 
100 

60 

•52 

72 


PER CENT, 
100 


Single riveted, hand, fig- 
ure 19 


50 


Single riveted, machine, 
figure 19 


49 


Double riveted (chain), 
Figure 20 


67 







We thus have an average gain by chain riveting over 
single riveting in 



SHEARING TESTS OF IRON. 113 

One-half inch plates of ...>: 19 per cent. 

Seven-sixteenths inch plates of. 18 per cent. 

Three-eighths inch plates of. 16 per cent. 

These joints were all made with three-quarter inch rivets, 
arranged in the specimens at two-inch centers. 

Testing rivets — The strength of a riveted joint depends 
so much on the strength of the rivets which enter into it, 
that it is of the utmost importance to know the quality of 
the materials of which they are made, before putting any 
work on them. One of the simplest and at the same time 
a severe test, is to upset a rivet on an anvil under a heavy 
hammer, say to one-half its original length and without 
splitting it. The writer has employed this test in deter- 
mining the quality of supplies, and finds that specimens 
selected at random, and which will stand this test, have 
usually all the- other qualities of a good rivet; but as the 
strain brought upon rivets is that of shearing, tests should 
be made to determine the resistance to the separation of 
the rivet at the line of plates composing the joints, which 
may be either single or double shear, the former being the 
ordinary practice in this coun- 
try, the latter the exception. ^^^^^^ 

Single shearing is clearly ^^^^Iflil^^^^ 
shown in figure 21, which repre- \ J lJ' Ji " ' '^M 

\\,\\7 il'/m/ 

sents a rivet in a single riveted ■ 'Si^ 

. . , 1 . . Figure 21. 

joint, undergoing separation. 

Mr. Wm. H. Shock, chief engineer U. S. ]^., made some 
shearing tests of iron for stay bolts with results as given 
below. This quality of iron is not as high as that usually 
employed in the manufacture of rivets, but still of good 
quality. The iron was made up into bolts with nuts, instead 
of being riveted into the testing plates, as is the usual 
practice. There were sixty of these bolts in all ; twelve 



114 



A TREATISE ON STEAM BOILERS. 



each of the following sizes, viz : one-half, five-eighths, 
three-quarters, seven-eighths and one inch diameter. These 
were forged in the usual manner, without any reference 
whatever to the experimental tests to be made. The fol- 
lowing table gives the results of the tests : 

TABLE XXXVI. 

RESULTS OF EXPERIMENTS ON SHEARING STRAINS OF IRON BOLTS, HY 
AVILLIAM H. SHOCK, CHIEF ENGINEER, UNITED STATES NAVY. 



SINGLE SHEAR. 



K ■ 



1 to 6. 

7 to 12. 
i:{ to 18. 
19 to 24. 



DOUBLE SHEAR. 



S f- w 

h3 -^ " 



.515 
.646G 
.7833 
.9033 



25 to .30 11.036 

I 
Mean of the above.! 



H 
Q 



9183.3 
12808.3 
19025. 
26562.5 
34358.3 



<; !z; i^ 
3 -I g 

■^ i^ o 



O H 



1^ ■ 

*l IB CC 

?. li< "^ 

< o 

g a o 

fe O (1, 

z a 

- << o 



.20831 
.32837 
.48192 
.64089 
.84395 



W CO 
M 

44,085 
39,00C 
39,477 
41,446 
40,071 
40,817 



a . 
S5 



31 to 36 
37 to 42 
43 to 48 
49 to 54 
55 to 60 
Mean 



H 

^ W t-H 

h; fe '^ 

<! O iz; 

H 
o 



.51 
.635 
.7766 
.9166 
1.035 
of the 



C5 

O 



16766.6 
24442 
37700 
50021 
63246 
above. . 



a 

-^ ;?; 
o a 

C 



.40856 

.63338 

.94751 

1.31988 

1.68268 



r '=^ • 

« W CO 

« a o 

H o t- 

C5 -■ S 

« =*= S 

a P &H 



41,036 
38,589 
39,789 
37,822 
37,586 
38,984 



Mean of both sets, 



40817 + 3 8 8 4 



-o^iio^ = 39,900. 



The tensile strength of rivet and stay bolt iron will 
average higher than what is known as the best merchant 
iron, or that employed in the experiments of Mr. Shock. 
Many manufacturers make a special grade of iron for this 
purpose, some of which is maintained with great uniform- 
ity of quality. The tensile strength of iron or mild steel 
is not in all cases a correct guide as to the shearing resist- 
ance of the same piece ; the common belief is, that they 
closely approximate each other. In the experiments of 
Messrs. Grieg and Eyth to determine this, in which two 



TENSILE AND SHEARING TESTS. 



115 



sets of tests were made on both iron and steel, one to deter- 
mine the tensile strength and the other to determine the 
shearing resistance of specimens taken from the same bar, 
the folio wino: averasre results were obtained: 

TABLE XXXVII. 

TENSILE TESTS OF RIVET IRON. 



DIAMETER | IX. =0.307 SQ IN. AREA. 



Breaking strain per section 

Breaking strain per square inch... 

Reduction of area, per cent 

Elongation in 10 in. (orig. length). 



STEEL. 



19,869 pounds. 
64,579 pounds. 
30.1 
2.06 inches. 



IRON. 



15,320 pounds. 

49,795 pounds. 
42.03 

2.78 inches. 



It will be observed that the tensile resistance of the 
steel is thirty per cent higher than the iron. 

In the shearing tests of rivet iron and steel the diam- 
eter of the bars of rivet material were five-eighths inch ; 
the area sheared through being 2 X 0.3068 = 0.6136 square 
inch. 

STEEL. IRON. 

Average shearing strain 30,486 lbs. 26,130 lbs. 

Shearing strain per square inch.. 49,683 lbs. 42,582 lbs. 

These specimens were subjected to a double shearing 
strain in a simple apparatus, consisting merely of two 
three-eighths inch steel plates, fixed at a distance of three- 
eighths of an inch apart, so as to permit another three- 
eighths inch steel plate to slip in between the first two. 
These three plates were then perforated by a five- eighths 
inch drill and the specimen inserted in the hole ; the two 
outside plates were then pulled by the testing machine in 
one direction and the plate between them in the other. 
Thus the specimens were in double shear, two sections 
being sheared clean through during the process of testing. 



116 A TREATISE ON STEAM BOILERS. 

When tested in this way the steel rivets showed an average 
shearing resistance of 49,688 pounds per square inch, the 
iron of 42,582 pounds. Thus the shearing resistance of 
the steel was only 17 per cent higher than that of the iron. 
This explains how it is that in the test pieces representing 
riveted seams, given elsewhere in this chapter, that the steel 
specimens, as a rule, broke by shearing of the rivets and 
the iron by tearing the plate through the holes. It is also 
worth noting how far from the truth is the rule so fre- 
quently adopted, which assumes the tensile resistance of 
iron or steel to be about equal to the shearing resistance, at 
any rate in cases of double shear. In the present case the 
latter proved far less than the former; in the case of iron 
by 16 per cent, in the case of steel by 28 per cent, showing 
besides that the shearing resistance does not bear any fixed 
proportion to the tensile resistance. 

The shearing resistance of the bars of iron and steel 
having been concluded, Messrs. Greig and Eyth then inves- 
tigated the shearing resistance of rivets actually formed. 
For this purpose three steel plates (three-eighths inch 
thick) were riveted together in a manner analogous to 
that already described. • The rivets intended to be tested 
were so-called five-eighths inch rivets, inserted into drilled 
holes of eleven-sixteenths of an inch in diameter. It was 
thought of some interest to ascertain the effect of different 
methods of riveting. These are given below: 



SHEARING RESISTANCE OF RIVETS. 



117 



TABLE XXXVIII. 

SHEARING RESISTANCE OF IRON AND STEEL RIVETS, FIVE-EIGHTHS OF 

AN INCH IN DIAMETER. 

Greig and Eyth. 



MATERIAL OF 
RIVET. 


METHOD OF MAKING 
THE RIVET. 


SHEARING 
STRAIN OF 
SPECIMEN. 


AVERAGE. 


AVERAGE 

SHEARING 

STRAIN PER 

SQUARE INCH 


Iron 


Hand riveting 

Hydraulic riveting... 

Steam riveting 

Hand riveting 

Hydraulic riveting... 
Steam riveting 


POUNDS 

33,488 1 
34,.552 \ 
35,862 J 
42,392 1 
43,288 ■ 
45,696 J 


POUNDS. 
34,630 

43,646 


POUNDS. 


Iron 


46,646 


Iron 




Steel 




Steel 


58,790 


Steel 









Holes drilled eleven-sixteenths- of an inch in diameter. The actual section sheared 
through, two circles of eleven-sixteenths of an inch in diameter, or 0.7424 square inch. 

The shearing resistance of these six rivets, as will be 
seen, showed a considerable increase over that of the sim- 
ple bar not yet formed into a rivet, which is due partly to 
the increased sectional area of the material, which now fills 
an eleven-sixteenths inch hole, and partly to the friction 
between the plates held together by the rivets. It should 
be noted, however, that this increase is much greater in the 
case of steel than of iron. 

The following table gives the results of experiments 
made on twelve specimen rivets (steel), having a nominal 
diameter of five-eighths of an inch, the actual section 
sheared through being two circles of eleven-sixteenths 
of an inch i'n diameter, or 0.7424 square inch. This series 
of tests were undertaken because of the striking regularity 
with which the experiments recorded in table XXXVIII 
showed as to the relative strength of hand, hydraulic and, 



118 



A TREATISE ON STEAM BOILERS. 



steam riveting, both in iron and steel. Four different 
machines were employed, in which the pressures on the 
rivet heads were as follows : 

Steam riveter 82,380 lbs. 

Tweddell's stationary machine 86,360 lbs. 

Tweddell's portable machine 42,018 lbs. 

McColl's power riveter, light blow 69,384 lbs.. 

McColl's power riveter, heavy blow 115,640 lbs.. 

It was considered most likely that the pressure which 
is brought to bear on the rivet head whilst forming, must 
have a considerable influence on the quality of the rivet ; 
hence these tests. 



TABLE XXXIX. ^ 

EIVET TESTS. 

All rivets of steel. Diameter of rivet steel, f inch ; diameter of hole, j^ inch'. 
Section sheared, two circles of ^^ inch diameter, = 0.7424 square inch. 
Shearing strength of the original steel bar, 49,683 pounds per square inch, or 36,885 
pounds for 7424 per square inch. 

Tensile strength of steel, 64.579 pounds per square inch. 
Each figure of the table represents the average result of three specimens. 

Greig and Eyth. 



IV 



METHOD OF MAKING THE KIVET. 

Pressure on rivet head 

Breaking strain of sample 

Shearing strain of steel in sample.....' 

Frictional resistance of sample 

Frictional resistance between two surfaces 



I 


II 


III 


STEAM. 


HYD. 


HYD. 


LBS. 


LBS 


LBS. 


82,380 


86,360 


42,018 


42,717 


39,491 


37,811 


36,885 


36,885 


36,885 


5,832 


2,000 


926 


2,916 


1,303 


463 



POWER POWER 



LBS. LBS. 

69,384 115,640 



37,341 

36,885 
456 
228 



39,424 

36,SS5 
2,. 539 
1,269 



In regard to results obtained, taking columns I, II and 
V of the above table into account, because columns III and 
IV refer to rivets closed under exceptionally low pressure, 
the average breaking strain of the samples riveted by 



STEEL RIVETS. 119 



steam, hydranJic or power pressure amounted to 40,544 
pounds, whilst the mere shearing resistance was 36,885 
pounds. The average frictional resistance, therefore, is 
3,659 pounds. Thus it appears that on an average the 
shearing resistance of a five-eighths steel rivet is made up 
of 91 per cent of direct resistance to shearing and 9 per 
cent of frictional resistance. This, of course, assumes that 
the direct shearing resistance is the same after the material 
has been made into a rivet, as before. 

Steel rivets have been but little used and have never 
been in favor until quite recently. The same faults existed 
in rivets which were found in the earlier steel plates, viz : 
high tensile strength and low ductility; to this must also 
be added improper working in the boiler shop. From the 
results of recent practice there is reason to believe that 
mild steel possesses every requisite for a good rivet. The 
tensile strength should not be much above 58,000 pounds 
per square inch and should be tough enough to rivet cold. 
In using steel rivets in the boiler shop they should be 
uniformly heated throughout, and not the points merely, 
as is the ordinary method of heating iron rivets; neither 
should they be heated as highly as iron rivets and should 
never exceed a bright cherry red. Particular attention 
must be given to the thickness of the fire ; steel, of what- 
ever kind, should never be heated in a thin fire, especially 
in one having a force blast, such as an ordinary blacksmith 
or riveting fire. The reason for this is, that more air passes 
through the fire than that needed for combustion, and in 
consequence there is a considerable quantity of free oxy- 
gen in the fire which will oxidize the steel, or in other 
words, burn it. If excluded from this free oxygen steel 
can not be burned ; if the temperature is high enough it 
can be melted and will run down through the fire, but 
burning is impossible in a thick fire with a moderate draft. 



120 



A TREATISE ON STEAM BOILERS. 



This is an important matter in using steel rivets and 
should not be overlooked; the same principle applies to 
the heating of steel plates for flanging. 

Tables XL and XLI give the results of mechanical 
tests made on American rivet steel. The first table gives 
results by means of a Thurston torsional machine, the 
latter on one by Riehle Brothers. 



TABLE XL. 

TORSIONAL TESTS OF BESSEMER RIVET STEEL MADE BY THE EDGAR 
THOMPSON STEEL WORKS. 

{Specimens five-eighths inch diameter , one inch long between shoulders). 



Angle of torsion 

Moment of torsion 

Tensile strength at elastic limit.. 

"Ultimate tensile strength 

Per cent of elongation (torsional) 
Carbon in the specimens 



1 



351° 

281 ft. -lbs. 
35,998 lbs. 
56,913 lbs. 

116 
0.11 percent. 



423° 

291 ft.-lbs. 
37,886 lbs. 
43,500 lbs. 

150 
0.14 percent. 



.337° 

298 ft.-lbs. 
37,883 lbs. 
56,004 lbs. 

109 
0.15 percent. 



Samples of the 0.11 and 0.14 per cent rivet steel, turned 
to one-half inch diameter and three inches between 
shoulders, were tested by Mr. Borntraeger on a Riehle 
Brothers' testing machine, with results as below: 



TABLE XLL 

TENSILE TESTS OF BESSEMER RIVET STEEL MADE BY THE EDGAR 
■ THOMPSON STEEL WORKS. 



SAMPLES. 


1 


2 


■ 

Carton in samples 


0.11 pr. ct. 
3 inches. 
^ inch. 
.1963 inch. 


0.14 pr. ct. 
3 inches. 


Length of samples 


Diameter of samples 


4 inch. 


Area of sample 


.1963 inch. 







SINGLE RIVETED LAP JOINTS. 



121 



TABLE XLI— CoxTiNUED. 



SAMPLE.S. 



Elastic limit of sample 

Elastic limit per square inch 

Weight at which sample broke..., 
Tensile strength per square inch. 

Elongation 

Elongation, per cent 

Diameter of reduced section 

Area of reduced section 

Percentage of original area 

Percentage of reduction 



8,200 lt)s. 

41,772 lbs. 

12,500 n)s. 

63,678 tt>s. 
f in 3 inches. 

29 

.35. inch. 

.096 inch. 

49 

51 



7,500 fl)s. 
38,206 lbs. 
11,750 11>s. 
59,850 His. 
11^ in 3 inches. 

28 

.33 

.086 
43.6 
56.4 



inch, 
inch. 



Single riveted lap joints — This is the simplest form of 
a riveted joint and is used almost exclusivel}^ in riveted 
seams in boiler shells when of forty inches or less m 
diameter. Some manufacturers begin double riveting at 
thirty- six: inches, but this is the exception rather than the 
rule. The single rivited joint, though easily made, is at 
best but about one-half the tensile 
strength of the solid plate. Among 
the defects of construction may be 
mentioned the liability of tearing 
the plate through the line of rivet figure 22. 

holes, as shown in tigure 22. This is liable to occur in 
any case where the rivet holes are punched too close 
together, thus reducing the strength of the plate below 
the shearing strength of the rivets. This is a fault which 
one may be easily led into and is perhaps the commonest 
defect in boiler construction. 




122 



A TREATISE ON STEAM BOILERS. 




Figure 23. 



Another cause of failure, though 
not nearly so common as the former, 
is that of punching the holes too 
near the edge of the plate. When 
the distance from the edge of the 
rivet is too near the edge of the 
plate the latter is likely to give way in front of the rivet, 
as in figure 23. This defect is easily remedied by simply 
allowing a wider margin; and in consequence may be 
easily overdone, for if the edge of the plate be too far from 
the joint it makes calking the joint steam tight a much 
more difficult matter, owing to the spring or elasticity of 
the plate. On the other hand, if the rivet holes have 
their centers too far apart and the distance from the edge 
of the hole to the edge of the plate be such that the plate 
can not yield, as in figures 22 and 
23, then there is a possibility of .,.._-.^SII 




shearing off' the rivets, as in figure '^ 

24. This is likely to occur when 

the rivets are too small in diara- figurr 24. 

eterfor the thickness of the plate. 

The ultimate strength of a plate depends upon its area 
of cross section ; and the loss of area caused by punching 
the holes for the insertion of the rivet, reduces the strength 
of the plate simply in that amount. With rivets, however, 
the case in quite dissimilar, for the strength of the rivet 
increases as the square of its diameter. In the former case 
the strength of the plate consists merelj^ in that of the net 
area through the line of rivet holes; in the latter the resis- 
tance to shearing increases with the increased area of 
the rivet. Other things being equal, that is the best joint 
in which the strength of the plate and the resistance of the 
rivet to shearing are equal to each other. Hundreds of 
tests have been made to determine by direct experiment 
the best proportions for single riveted joints. 



PROPORTIONS FOR RIVETED JOINTS. 123 

The differences in quality of boiler plate and rivets, 
together with the great uncertainty as to the exact effect 
of punching iron plates, have, so far, prevented anything 
like the determining either by calculation or experiment 
of what might be accepted as the exact, or better, perhaps, 
the best proportions for riveted joints. The writer has 
examined many formulas and finds that in most cases they 
are suited only to the one or two thicknesses of plates for 
which they were evidently intended, being usually three- 
eighths and seven-sixteenths inch, and have the appear- 
ance of having been worked out for the seams in Cornish 
or other large diameter internally fired boilers. 

The thinner plates, one-fourth inch, for example, in 
English tables of proportions for riveted joints, give one- 
half inch as the proper diameter of rivets. This is not in 
accordance with American practice; five-eighths inch 
rivets in one-fourth inch plates being almost universal. 
The spacing of rivets is also greater in this country than 
in England. 

The following tables were compiled by the writer for 
his own use, partly from theoretical deductions, partly from 
tests made on riveted joints, and also by a comparison of 
these with the practice of successful and intelligent manu- 
facturers. It will be observed that the dimensions are 
empirical, yet they have served a good purpose and on the 
whole are quite reliable. This matter of spacing rivets is, 
at best, approximate only, and may be changed within 
narrow limits ; it often happens that spacing will not come 
out even, and in such cases, whether the centers shall be 
increased or decreased, rests entirely upon the judgment of 
the designer. In general, it has been the practice of the 
writer to use the proportions in the table, and when spaces 
occur at the end to put in the extra rivet instead of throw- 
ing it out. 



124 



A TREATISE ON STEAM BOILERS. 



TABLE XLII. 

SHOWING DIAMETER AND SPACING OF RIVETS IN SINGLE RIVETED 

LAP JOINTS. 



•THICKNESS 


DIAMETER 


LENGTH 


CENTER OF 

RIVET 

TO EDGE OF 

PLATE. 


CENTER TO 


OF 
PLATE. 


OF 
RIVET. 


OF 
RIVET. 


CENTER 
OF RIVETS. 


^ inch. 


^ 


1 


13 

T6 


u 


^ inch. 


1 


n 


] 


If 


^ inch. 


5 

8 


n 


1 


n 


f inch. 


f 


If 


lA 


2 


^^ inch. 


3 

4 


2 


1t^ 


91 

^8- 


^ inch. 


7 
8 


2i 


1 3 


93 


-^ inch. 


"8 


2^ 


1 3 
^ 8 


01 

-■2" 


f inch. 


] 


2f 


1 3 


2f 


^^ inch. 


1 


3 


ll^ 


2| 


f inch. 


H 


3} 


If 


3 



Double riveting — Boilers ought to be double riveted, if 
for no other reason, simply as a matter of economy, for 
the strength of the single riveted joint, which is only 
about one-half the strength of the solid plate, is increased 
by about twenty per cent by double riveting, without any 
such corresponding increase in cost. 

The strength of a joint depends largely upon the 
strength of the rivets, and these must be so disposed in the 
joint as to utilize the strength of a larger number than 
can be used in single riveting, and at the same time 
increase the net sectional area of the plate in the line of 
punched holes in the joint. The waiter does not think it 
a good plan to change the diameters of rivets in fixing 
upon single or double riveted joints. The two tables 
therefore contain the same diameters of rivets for the 
same thickness of plates. 



DOUBLE RIVETED LAP JOINTS. 



125 



TABLE XLIII. 

SHOWING DIAMETER AND SPACING OF BIVETS IN DOUBLE RIVETED LAP 

JOINTS. 




Figure 25. 



THICKNESS 


RIVETS. 


CENTER TO 


CENTER 


CENTER 


CENTER 


OF 




EDGE OF 


TO 


TO 










PLATE. 


DIAMETER 


LENGTH. 


PLATE, 


CENTER. 


CENTER. 


CENTER. 


A 


B 


b 


C 


D 


E 


F 


i 


8 


^ 




2 


n 


1 9 
^T6 


5 
ITT 


f 


n 




2i 


2 


1 21 
^3T 


3 

8 


1 


If 


1 3 


2| 


9 1 

^ 8" 


123 
^3^ 


7 


3 


2 


1 3 


2| 


9 1 


If 


1 


7 
'8 


2i 


1 •i 

J 8 • 


3 


9 7_ 
'■le 


129 
^32 


9 - 
TIT 


7 
"8 


^ 


1 '^ 
' 8 


3i 


2A 


2 


5 

8 


] 


93 


1 ■> 


3* 


2f 


2i 


11 
TIT 


1 


3 


1 •> 


3f 


2f 


2A 


1 


H 


^4 


1 ^ 
-^ 4 


4 


3 


2i 



Tbe distance F is approximate only, column E being the exact distance. 



Calking — In boiler making calking is a process of 
upsetting the overlapping edges of plates by means of a 
tool called a calking chisel. A full size representation of 
the calking end is given in figure 25 and marked '^old 



126 A TREATISE ON STEAM BOILERS. 

style calking." When two rough boiler plates are riveted 
together they are not .steam tight; the object of calking is 
to "upset" the edge of the overlapping plate and drive it 
firmly down upon the one underneath. This operation 
does not, of course, alter the character of the joint; it sim- 
ply forces the edge of the outside plate down firmly upon 
the lower one and thus a joint at first approximately tight 
is rendered altogether so by this simple operation. 

The edges of plates ought always to be planed or 
sheared to the proper bevel for calking before riveting 
together. The angle of plates best suited for calking is 
about 20° less than a right angle. The practice of chip- 
ping seams after riveting is altogether wrong, as it 
endangers the strength of the plate underneath by the 
frequent and inevitable markings caused by the slipping of 
the chisel in the hands of the chipper. The markings are 
ruinous to the plates containing them, and are, no doubt, a 
frequent cause of disaster. Aside from the injury done 
the plates by careless chipping, the operation of calking 
by means of a sharp edge, even though it approximate a 
right angle, is also destructive to the lower plate, by form- 
ing a slight indentation the v^hole length of the seam so 
operated upon. An improved form of calking, patented 
by Mr. James W. Connery, Philadelphia, Pa., is shown in 
figure 26, and named by him "concave" calking, after the 
appearance of the finished joint. 

The object of concave calking is to bring together the 
seams of a boiler after riveting, in such a manner that they 
shall be perfectly steam tight and at the same time not in 
any manner injure the under sheet. This is eiFectually 
accomplished by the use of a tool with a semi-cylindrical 
end, producing a concave depression in the bevelled edge 
of the lap ; slightly dividing the plate calked and driving 
the divided part towards the rivets, forming a bearing from 
one-half to three-quarters of an inch, thereby forming a 



concavp: calking. 



127 



proper junction of the two surfaces and increasing the 
strength of the joint, without in any manner injuring the 
surface of the under plate. 

The accompanying cut illustrates the difference between 
the old and the new systems. 




Figure 2g. Full Size. 



The old plan is to chip or plane the edge of the over- 
lapping sheet, leaving a solid angle to it of about 80°, and 
then to drive up, by means of a hammer upon the tool 
shown at the right, the under face of the tool resting upon 
the under sheet, until the angle of the metal of the upper 
sheet has assumed something near the form there shown. 
With a tool of this form it is impossible to thorough!}^ 
upset or calk the metal of the upper plate without a more 
or less injury or scoring of the Under plate; and this will 
not be the only injury done the under sheet, for it is weU 
known that in all processes of hammering, rolling and 
otherwise compressing iron, it becomes harder and more 
dense, and as there is nothing in the process of calking 
with this tool which makes any change in the material of 



128 A TREATISE ON STEAM BOILERS. 

the under plate, it follows that after indentations and chan- 
nel] ngs are made in the under plate by the calking tool, 
the extreme edge of the upper plate, while being hardened 
and compressed, will be imbedded in the under plate, thus 
aggravating the injury done with the tool. These effects 
are plainly shown in plates which are cut apart after the 
most careful calking, and is well illustrated in the figure as 
giving to the plate that starting point of fracture with 
which all mechanics in metal are familiar. With Connerv's 
improvement a concave depression is produced in the bev- 
elled edge of the lap, the crown of the tool being entered 
in the edge of the plate at such a distance from the under 
plate as will leave, when finished, a considerable thickness 
of metal between the concave groove and the lower plate ; 
the surface of the compressed and hardened metal, driven 
down upon the lower plate, will be too large to cause any 
appreciable disturbance of the surface of the under plate, 
while the tool can, under no circumstance, injure or mar 
the lower plate in any way. 

It will be readily seen, too, that this form of tool, com- 
mencing as it does on a small surface for indentation of the 
edge, must result in carrying the compression or condensa- 
tion of the iron of the lap to a much greater depth than 
is possible with the old method, thus tending to bring 
about a permanent strain upon the iron through the line 
of rivets in a much less degree. This is indicated on the 
left of the cut by the deep wedge of dark shading running 
nearly into the rivets. 

Many of our first class establishments have adopted this 
method of calking, among which is the Baldwin Loco- 
motive Works of Philadelphia, who have been using this 
improvement exclusively for several years upon their hun- 
dreds of locomotives and indorse it in the highest degree. 

The writer is so fully impressed with the value of thi& 
invention that he does not hesitate to recommend it in all 



CONCAVE CALKINa. 129 



cases as being superior to any other method of calking of 
which he has any knowledge; such a thing as grooving or 
injuring the lower plate by calking being practically 
impossible, and w^hich gives this invention its chief value. 

The following tests were made at the Washington E^avy 
Yard: "Five plates of different thicknesses were riveted 
together and the four seams on one side were calked by the 
Connery process, and those on the opposite side (by differ- 
ent boiler makers employed in the yard) by the ordinary 
process. Upon cutting the sheets apart, in every case, it 
was found that the bearing surfaces of the sheets were 
about double that of the seams calked by the ordinary 
method, and that there was no injury done to the under 
sheets, whereas the under sheets of the seams calked in the 
ordinary way were slightly indented in some cases, and in 
others were channeled or grooved about one-thirty-second 
of an inch in depth, depending upon the skill and care of 
the workmen employed. Several seams were also calked 
by the above process on an experimental cylinder which 
was subsequently tested to its collapsing pressure of one 
hundred and thirty-four pounds per square inch, without 
the slightest leak, whereas a number of leaks made their 
appearance in seams calked by the ordinary process." 

Locomotive boilers tested by hydraulic pressure to 
more than three hundred pounds per square inch, and 
afterwards used with a steam pressure of one hundred and 
fifty pounds, showed no leakage at seams with this calking. 

'No joints in a boiler are more difficult to get tight 
than those which are single riveted. This is due to a par- 
tial distortion of the joint, caused by the shell of the boiler 
assuming a more perfect cylindrical form when pressure is 
applied than that given it in the boiler shop during the 
process of manufacture. 

Figure 27 shows, by means of the dotted lines, the 
curved surface of the cylindric part of the shell, and the 
(10) 



130 



A TREATISE ON STEAM BOILERS. 



full lines the actaal positioa of the joint; and it is just 
here that the mischievous effects of the grooving caused 




Figure 27. Full Size. 



by chipping and sharp calking become fully apparent, and 
which is shown in an exaggerated degree in figure 26, by 
the breaking of the plate. 



CHAPTER VII 



WELDING, FLANGING AND INFLUENCE OF TEMPERATURE. 

Welding Boiler Plates — Advantages Claimed — Objections to Welding 
Externally Fired Boiler Shells — Practical Difficulties in Welding 
Long Seams — Strength of Welded Joints — Welded Rings for 
Boilers — Flanging — Influence of Temperature on Boiler Plates — 
Mr. Isherwood on the Franklin Institute Experiments of 1837. 

Welding boiler plate joints — -.Very little attention has been 
given in this country to the production of welded boiler 
plate joints. The few experiments that have been made 
have been so crudely done that no intelligent opinion can 
be formed as to the relative costs of welded and riveted 
work. In England welded joints have been in use for sev- 
eral years and for some purposes is steadily growing in 
favor, though it is not practiced in boiler construction to 
any great extent as yet. 

The advantages claimed for this form of joint over the 
ordinary riveted joint are, 

1. That the welding approximates more clearly the 
original strength of the plates than the best forms of riv- 
eted joints can possibl}^ do, besides being entirely free from 
the bad eflects of punching and loss of strength occasioned 
by drifting, as well as the injury done the plates by cold 
hammering. 

2. The welded joint needs no calking, and thus, next 
to drifting, one of the greatest evils through bad workman- 
ship in boiler construction is rid of entirely. 

3. By welding the rings in the shell of a boiler they 
may be re-rolled after the work is done on them, and thus 



132 A TREATISE ON STEAM BOILERS. 

a perfectly cylindrical shell can be produced, a thing^ 
impossible in the ordinary lap joints. 

If an entire shell could be welded, it would remove at 
once the objectionable two thicknesses of plate in the fire 
and the trouble incident to the accumulation of deposit 
which is likely to form around the joints iind rivet heads; 
and, further, there being no jointed seam, entirely precludes 
such a thing as corrosion caused by leakage at the lap of 
the plates or around loose or imperfectly fitted rivets. 

Whether a welded joint is to be preferred over a riv- 
eted one, will depend upon circumstances. In an inter- 
nally fired boiler it is important that the main flue should 
be truly c^^lindrical, as the resistance to collapse depends 
largely upon this. The best makers usually employ in its 
construction a butt riveted joint with the seam underneath. 
The objections to this are, that it is impossible to perfectly 
calk such a seam when once in place; and then the seam 
of rivets along the bottom of the flue will prevent the 
ready removal of ashes and dust which accumulates along 
its whole length. Should there be a leaky joint, a thing 
we may almost certainly count on, there will in time be 
quite an accumulation of hard baked ashes and cinders 
the whole leno^th of the flue. In case the fuel used con- 
tained sulphur, there would be more or less of sulphurous 
oxide mixed up with the ashes or deposited along the sides 
or bottom of the boiler flue, and which, if once wet or 
dampened, will attack the flue by external corrosion and 
seriously impair its strength. In such a case a welded and 
perfectly tight flue would possess a marked advantage over 
the other, to say nothing of that gained by tbe truly cylin- 
drical form; this advantage, it should be understood, refers 
to the facility and certainty in cleaning and freedom from 
leaks, and not that the corrosive action would be less under 
the same conditions. 



WELDING BOILER PLATES. 133 

In such a flue, as just described, the pressure tends to 
collapse and thus to tighten the weld. An imperfect weld 
might, in such a flue, escape detection for a long time, but 
which would soon make itself apparent in any case where 
internal pressures were employed. 

In externally fired boilers, the main advantage of welded 
seams over riveted ones appear to be the getting rid of all 
the double thicknesses of plates in the fire. This is at all 
times a desirable thing to do. In boilers of this type, the 
straii>s are from within, outward, and the safety of the shell 
depends entirely upon the tensile strength and ductility of 
the plates and the soundness of the weld. The strength 
of a riveted joint is known to within a very small percent- 
age of the weight required to tear it apart. For welded 
joints, unfortunately, no such exact data exists, and from 
the nature of the joint it is exceedingly difl3.cult to arrive 
at anything even approximating its actual strength ; not 
that experimental tests are wanting, nor that suflicient 
time has been denied the subject in order to make the 
fullest investigation in regard to the effect upon the plates 
joined by welding, the weld itself, or the proper mechanical 
manipulation of the plates in the fire. We have all this, 
and it only goes to show what the possibilities are, but 
gives no data as to probabilities in actual practice, on a 
large scale, with even good facilities and skilled workmen. 

The welding of two plates in a well made open fire is 
attended with greater- risks than the welding of two bars 
of iron. The reasons for this are quite obvious. In the 
case of the bars, their ends are in the center of the fire and 
entirely shut off" from the injurious eff'ects of free oxygen, 
if the fire is properly made. When a thick fire is built 
upon the tweer, the air passing up through it gives up its 
oxygen to the highly heated carbon, and carbonic acid gas 
is formed as the result of this union, and in passing up still 
further through this bed of burning coal, the carbon in the 



134 A TREATISE ON STEAM BOILERS. 

upper portion of the lire may take up a portion of the 
oxygen in the carbonic acid gas, and carbonic oxide gas. is 
formed. J^either of these gases has an injurious effect 
upon iron so far as welding is concerned, and in the case of 
the two bars referred to above, they are in this highly 
heated chamber of gases formed by the sides and cover of 
the fire, and may be readily brought to a welding heat 
without any fear of oxidation, for there is no excess of 
oxygen in the fire to come in contact with the iron. 

In the case of the plates it is somewhat different, for 
the fire being hottest in the center and of lower tempera- 
ture toward the edges, it is not possible to confine the 
plates to a chamber of heated gases from which oxygen is 
excluded, for no such chamber exists, and can not, from 
the nature of the case. Further, every movement of the 
plates brings the more or less highly heated portions in 
contact with the air, when oxidation instantly occurs, form- 
ing an oxide of iron or hard cinder which prevents welding. 
There is at the same time a partial loss of iron, but this is 
not of so much account as the bad effects resulting from 
the presence of the cinder in the weld. 

It is not practicable to heat any considerable length of 
plate in an ordinary forge or flanging fire at one time, and 
as the oxidation referred to is sure to occur in a greater or 
less degree, the surfaces must be protected from oxidation 
by means of a flux. The one generally used is sand; this 
is composed of silicon and oxygen. ' The action of the flux 
may be said to be two-fold : first, in forming a vitreous 
coating over the iron, and second, in reducing the temper- 
ature of the parts to which it is applied, and arises from 
the circumstance that iron is usually "scarfed" at the place 
where it is to be welded ; we thus have a thick and a 
thinner portion of the same plate exposed to the action of 
the heat, the thinner portion of the plate being nearest the 
center of the fire, and arrives at a welding heat long before 



WELDING BOILER PLATES. 135 

the thicker p.ortioa of the plate attains a similar heat. If 
the action of the heat was not checked, this thinner edge 
would be burned away long before the plate was brought 
to the welding point. In order to prevent this the sand or 
other flux is used, and in coming in contact with the highly 
heated iron it is melted and absorbs so much heat from the 
iron that it gives the latter a vitreous coating. This sili- 
cate combines with the iron and covers that portion of it 
which is of sufficiently high temperature to melt the sand. 
This silicate being of a very refractory nature, will last 
some time in the fire before it burns oiF the iron, and in 
this manner serves to protect the thinner parts of the iron, 
while the thicker portion is absorbing the heat and arriv- 
ing at a welding condition. 

In using sand as a flux, care must be exercised that it 
be kept, or afterward cleaned off, the inside of the joint 
where the two scarfed edges of the plate are to be welded, 
as its presence in the weld prevents perfect contact, and 
thus weakens the joint. For small work, borax is the flux 
generally employed in the forge for welding. It prevents 
oxidation in the same manner as already described for 
sand. 

There are many ways of making a welded joint and 
they will vary anywhere from good to bad in strength and 
soundness. Scarf welding is on the whole to be preferred 
to simply lapping the plates and then welding. In scarf- 
ing, the edges of the plates should be upset and then 
thinned down, not exactly to a sharp edge, but say one- 
sixteenth of an inch, or perhaps less. The exact thickness 
is of course no material part of the process of making a 
good joint ; neither is the thinning of so much importance 
as the upsetting of the edge of the plate to a thickness 
greater than that of the plate itself, the object being that 
when the weld is made it may then be finished down with 
suitable "flatters" to the regular thickness. 



136 



A TREATISE ON STEAM BOILERS. 



Ill the manufacture of welded boilers as a business, it 
would be necessary to construct a special heating appa- 
ratus, which would probably consist of an external and an 
internal gas furnace, operating on the principle of the 
blow pipe, in which the flame of the burning gas would be 
directed against such portions of the joint as needed the 
greater heat. Such an apparatus could be made in which 
no free oxygen could reach the heated plates, and thus 
welds could be made without the use of a flux of any 
kind. The plates could be heated the whole length at one 
time and when brought to the proper heat could be welded 
by pressure instead of by hammering. 

What the future may bring forth, it is impossible even 
to conjecture, but at present welded boiler plate joints, 
especially when intended for externally fired boilers, are 
untrustworthy and are almost sure to contain imperfec- 
tions in the weld which the usual hydraulic test fails to 
indicate, but which will reveal themselves sooner or later 
in the expansion and contraction incident to heating and 
cooling in actual service. 



Fjgure 28. 



Figure 29. 



Figure 30. 



In Mr. Bertram's experiments on welded joints the 
lap welded test pieces, figure 30, were inferior in strength 
to those scarf welded, figure 29. 



WELDING STEEL PLATES. 



137 



The specimens tested were four inches wide by three- 
eighths, seven-sixteenths and one-half inch in thickness. 
The lap of the joint was one and a quarter inches. 

The results were as follows : » 



TABLE XLIV. 



Strength of entire plate, per cent 

Strength of scarf welded joint, fig. 29, 
Strength of lap welded joint, fig. £0, 



f INCH 
PLATE. 



100 

Faulty. 
50 



/e INCH 

PLATE. 



100 

106 
69 



% INCH 
PLATE. 



100 

102 
62 



From the above data it appears that the strength of 
joints united by lap welding are scarcely better than single 
riveting, or about forty per cent weaker than the plates 
which compose the joint. Scarf welding, on the contrary, 
equaled the strength of the plate. 'No doubt the shape of 
the joint under severe stress had much to do with the low- 
ering of its strength in consequence of the indirect pull. 

In regard to the welding of steel boiler plates Mr. 
Daniel Adamson says: 

"After many trials and many failures in attempt- 
ing to weld steel boiler plates, the writer found it 
necessary to ascertain in all cases the composition 
of the metal before putting any labor on it, and from a 
large experience it is now considered desirable that the 
carbon should not exceed one-eighth of a per cent, while 
the sulphur and phosphorus should, if possible, be kept as 
low as .04 per cent, silicon being admissable up to the 
extent of -^^ of 1 per cent. Farther experience is yet 
required to ascertain what exact composition gives the 
most satisfactory results by welding. At present some 
preference may be said to be given to the Martin-Siemens 



138 A TREATISE ON STEAM BOILERS. 

class as compared with Bessemer metal, when both are of 
about the same chemical compositi-on." 

Weldle^s rings for boilers — Several years ago (1865?) Mr. 
Ramsbottom designed a machine to work annular ingots 
of Bessemer steel, or other metal, into cylinders of such 
length and thinness that they may be put between rollers 
and rolled round and round and reduced to the thinness 
required to make boilers. The machine consisted of a 
mandrel, on which the hoop or annular ingot was placed- 
On each side of tbe mandrel was placed a roller, the sur- 
faces of the roller and mandrel being grooved diagonally in 
opposite directions, thus leaving diamond shaped projec- 
tions on them. The rollers were intended to be driven by 
steam or other power, and were pressed against the hoop 
or ingot, which is enlarged in diameter and expanded 
lengthwise by the pressure and the lateral action of the 
projections on the rollers and mandrel. When the hoop 
or ingot has been thus partially expanded it was then to 
be put on another mandrel of larger diameter and again 
acted upon by the rollers; or it might be put on a revolv- 
ing mandrel and thus expanded both in length and 
diameter by a roller which is traversed to and fro in the 
direction of the axis of the hoop. In this arrangement 
the hoop and traversing roller must be pressed together. 

It has also been proposed and in a measure carried 
out, to forge the annular ingots by means of a steam or 
power hammer into the cylindrical sections of a boiler 
ready to rivet into a continuous shell. 

From the i)resent outlook it does not appear that either 
of these methods are likely to supersede the making up of 
Hat sheets into shells and large flues, because of the 
increased cost of manufacture of the cylindrical weldless 
hoops over that of flat iron rolled, and then riveted or 
welded. 



FLANGING. 13^ 



Flanging — The exterior flanging of a boiler head and 
small flue holes is about as severe a test as plate iron gen- 
erally receives in the process of boiler construction. By 
far the greater number of heads used in this country are 
hand flanged; there are very few boiler making establish- 
ments having enough flanging 'to do to warrant the 
erection of suitable furnaces and machines. The few 
machines which are in use, however, attest the superiority 
of machine over hand flanging. In the first place the 
heads are perfectly round, an important matter- of detail 
in boiler construction ; in the next j)lace the flange is 
turned perfectly true and at right angles to the face of the 
head. In hand flanging it is almost impossible to secure 
either or both of these in the same plate. The heating is 
done in the ordinary forge fire and liable to all the objec- 
tions of overheating one portion of the plate while other 
portions are not of sufficiently high temperature to insure 
the best working. 

In flanging an iron or steel plate, it should be done with 
wooden mauls, bending the plate over a cast iron former. 
The blows should be light and distributed over as large a 
surface as possible, avoiding anything like short bends in 
turning the flange. The heating, when done in an ordin- 
ary flange fire, must of necessity be local, and, hence, will 
require the greater care in working. As the flanging 
approaches completion by successive stages of heating and 
hammering, care must be exercised that the plate, if of 
steel, is not ruined by cracking or splitting, which may be 
induced by internal strains. To avoid this in subsequent 
working or handling, it should be immediately annealed 
by heating the whole plate gradually and evenly, until 
brought to a low red heat, and then allowing it to cool 
slowly, not disturbing it until entirely cold. 

The writer has used a considerable number of heads,, 
machine flanged, by Phillips, Nimick & Co., and aside from 




140 A TKEATISE ON STEAM BOILERS. 

the superior quality of "Sligo" iron, these heads seem to 
possess an advantage over the hest hand flanged work by 
the strengthening of the plate in the curve, as shovv^ii in 
the annexed engravings. 

Figure 31 represents the thinning of the curve occa- 
sioned by the stretching of the plate over the cast iron 
former in hand flanging, the dotted line representing the 
normal curve and the middle line the 
actual thickness of metal. Fiorure 32 
is a representation of the thickening 
of the curve, taken from machine 
flanged heads, made on the machine 
used by the above named firm. The 
normal curve, it will be noticed, falls 
considerably within the actual line of the metal. The 
advantages gained by the strengthening of the head at that 
particular point are quite obvious, and are not likely to be 
underestimated. 

Figure 33 is an engraving made from a photograph 
taken from a boiler head, and is, all things considered, 
one of the best specimens of machine flanging the writer 
has yet seen. The dimensions of the head are as follows 

Diameter outside, 72 inches. Diameter large flue, 40 inches. 
Diameter 2 holes, 12 inches. Diameter 2 holes, 8 inches. 

Diameter 6 holes, 6 inches. Diameter 1 hole, 5 inches. 

The influence of temperature on boiler plates — The influ- 
ence of diflerent temperatures on the strength of iron or 
steel is a question of great importance in engineering con- 
struction, and probably nowhere more so than in steam 
boilers. It is supposed that the efl*ect of repeated changes 
in the temperature of iron plates brings about certain 
molecular changes, which destroys the cohesion of the iron 
in the same manner that it would be destroyed by the con- 
tinued vibrations of a plate caused by any external force. 



INFLUENCE OF TEMPERATURE ON PLATES. 



141 



It is well known that the continued reheating and cool- 
ing of iron will shortly render it entirely worthless, if it 
approach a red heat. Plates cut out of that portion of 
old hollers suhjected to the action of the fire are almost 
invariably hard and brittle, and will seldom show one- 
fourth of its original ductility, together with a marked 
decrease in tensile strength. This can be referred to na 




FlGUKK 33. 



other cause than that produced by molecular changes 
brought about by the long continued action of the fire. 

Wrought iron is apt to blister or crack in overheating 
and changes its structure from fibrous to coarse granular,, 
losing in tensile strength and ductility and becomes^more 



142 A TREATISE ON STEAM BOILERS. 

brittle. The loss in tensile strength in overheated iron 
plates has doubtless been a cause of many boiler explo- 
sions and can only be explained by the possibility that the 
continued variation and diiferonces of temperature of the 
outer and inner surfaces of the plate have diminished 
the cohesion of the fibers or laminse composing it. 
If this is true of fibrous iron, what would be the effect 
of the temperature on granular iron? Sir William Fair- 
bairn ascertained, in his experiments, that on the whole 
cast iron of average quality loses strength when heated 
beyond a mean temperature of one hundred and twenty 
degrees, and that it becomes insecure at the freezing point 
or under thirty- two degrees Fahrenheit. Cast iron yields 
to the fire sooner than wrought iron ; it loses a consider- 
-able percentage of strength at about two hundred degrees, 
and when red hot will scarcely sustain its own weight. 
The effect of variations of temperature on mild steel has 
not been so closely observed as that on wrought iron, and 
while we have any reason to believe that molecular changes 
are undergone in the material in consequence of repeated 
heating and cooling, it does not appear that the strength 
is diminished in any considerable amount when the plates 
nre used in steam boilers. In case the boiler should become 
short of water, or in event of plates being overheated in 
such portions of the boiler as are not protected by the 
water, then the effect of excessive and continued over- 
heating is to render the plates coarse granular, losing in 
tensile strength and toughness. 

Wrought iron will the better withstand the effects ot 
repeated heating and cooling in proportion as it is free 
from cinder; hence, a tine granular and homogeneous iron 
will resist the bad effects of reheating better and longer 
than a course fibrous iron, because the latter is made 
fibrous by containing in its composition more or less cinder,, 
which, owing to the lower temperature of the finishing 



ANNEALING. 143 • 



heats, was prevented from escaping. As a result, it can 
never equal in strength and ductility the granular iron, and 
is apt, with even a moderate degree of overheating, to 
become extremely brittle ; and it is for this reason that it 
should never be used for the fire sheets of boilers. 

Heating to redness and slow cooling — or in other words, 
annealing — has an eflect on steel in which it is rendered 
more ductile than before, but at a reduction of its tensile 
strength ; such a plate once annealed does not apparently 
change by reheati'ng, unless the temperature is higher than 
that to which it was first brought. By this it is not to be 
understood that no molecular changes are going on in the 
metal because of the lower temperature, but rather that 
the destructive changes in steel plates are less in 
degree than in iron plates if there is no sudden cooling. 
Steel plates, in order to anneal them properly, should be 
brought up to a temperature higher than that at which 
the final work was done on them. A cherry red will be 
found to be somewhat higher than the final working heat, 
and in boilers higher than any subsequent heat. Steel 
plates must not be^ annealed at too high a temperature ; 
that is, the temperature must not be near the melting 
point, because it will change its texture and crystallize by 
slow cooling, thereby losing in tenacity, ductility and 
elasticity, rendering the plate worthless. . 

The operation of heating and sudden cooling produces 
efiects directly the opposite of the above, and its subse- 
quent behavior is not unlike that of similar pieces which 
have been brought to a strain exceeding the elastic limit; 
that is, the- tensile strength is increased, as is also its brit- 
tleness. Any metal, therefore, which will harden in 
cooling is not fit to enter in boiler construction because of 
this very property of becoming brittle and thus reducing 
its power to endure sudden variations in load or resistance 
to shocks. 



144 A TREATISE ON STEAM BOILERS. 

In regard to the accidental overheating of steel plates^ 
caused by low water, there have been many instances of 
collapse or of bulging, but such a thing as fracture in con- 
nection with overheating is almost unknown. 

Mr. Adamson observes that few or no malleable metalSy 
such as wrought iron or mild steels, can be found in the 
open market that possess a range of endurance at all vary- 
ing temperatures, say, from cold up to red heat, but nearly 
all ordinary bar or boiler iron and mild steels will endure 
considerable percussive force when cold and up to 450°" 
Fahrenheit, after which, as the heat is increased, probably 
to near 700°, they are all more or less treacherous and liable 
to break up suddenly by percussive action. The poorer 
class of metals at this temperature, which may be called a 
color heat, varying from a light straw" to a purple and dark 
blue, are simply rotten. Some of these peculiar properties 
are illustrated by a series of tests of various qualities of 
metal; for example: ordinary merchant iron shows that it 
may be bent cold, or it may be bent red hot without signs of 
breakage or much distress. Examples are not wanting to 
show that irons will endure this bending test when cold 
or when red hot, but such a heat as can be induced by 
placing the metal into a bath of boiling tallow, registering 
a temperature of about 610° Fahrenheit, these metals break 
through by being bent, lose most of their malleability and 
snap off short under the action of the hammer. 

The same unfortunate element is exhibited by the mild 
class of Bessemer and Martin-Siemens steel, with this dif- 
ference, that they bent better cold and more pleasantly 
when hot, but both break up by percussive action at the 
medium temperature before named, the Martin-Siemens 
enduring somewhat better than the Bessemer class under 
these tests. 

During several years of observation Mr. Adamson has 
come to the conclusion that no metal containing much 



INFLUENCE OF TEMPERATURE ON IRON. 145 

above a trace of sulphur can endure bending at this color 
heat, while at the same time the phosphorus must be low; 
in fkct, such endurance can only be obtained by a compar- 
atively pure iron, unalloyed by any other ingredients. 

Experiments made by Mr. Adamson, with bars of iron 
one inch in diameter and ten inches long between supports, 
when under tensile strain gave the following mechanical 
data : 

Permanent set induced per square inch. ...36, 287 pounds. 

Maximum strain per square inch 53,476 pounds. 

Elongation under maximum strain 18 percent. 

Final breaking strain on original area per 

square inch 50,929 pounds. 

Percent of elongation 20.5 

A piece of this same iron subjected to chemical analysis 
yielded, 

Iron 99.44 

Carbon trace 

Manganese 0.10 

Silicon 0.16 

Sulphur 0.01 

Phosphorus 0.29 

100.00 

This iron was tested with a view to examine its power 
of endurance at a low heat, and at temperatures varying 
from 500° to 600° Fahrenheit it was found very difficult to 
get a bent piece ; and by referring to the composition of 
this iron, it will be found to contain a large measure of 
phosphorus, which in some degree may explain its lack of 
power to resist percussive force at the heats just named ; 
nevertheless, this cheap ordinary iron is much more 
valuable for many practical purposes than pure and com- 
paratively expensive wrought irons.. 

Franklin Institute experiments — The influence of temper- 
ature on the strength of wrought iron boiler plates was 

(11) 



146 A TREATISE ON STEAM BOILERS. 

investigated in 1837 by a commitee of the Franklin Insti- 
tute and their conclusions were, that, the tenacity of boiler 
plates increased with the temperature up to five hundred 
and fifty degrees Fahrenheit, at which point the tenacity 
began to diminish. The tensile strength per square inch 
of section 

At 32° Fahrenheit was 56,000 pounds. 

At 570° Fahrenheit was 66,500 pounds. 

At 720° Fahrenheit was 55,000 pounds. 

At 1050° Fahrenheit was 32,000 pounds. 

At 1240° Fahrenheit was 22,000 pounds. 

At 1317° Fahrenheit was 9,000 pounds. 

Mr. Isherwood, in a contribution to the Franklin Insti- 
tute Journal in 1874, shows, in a very convincing manner, 
that the committee erred in judgment in continuing the 
experiments with the same specimens successively after 
rupture. He says : 

" In the experiments the same piece of iron was suc- 
cessively ruptured and gave as a general result just what 
might have been expected, namely, increased tenacity at 
each rupture under ordinary atmospheric temperatures; 
but the committee failed to detect the reason and left the 
naked fact standing in their tables without explanation. 
The experiments made by the committee under high tem- 
perature were vitiated by the same cause, as they were 
made on the same piece of iron after it had been broken — 
often several times — under low temperatures. The com- 
mittee did not perceive that the greater tenacity of the 
iron observed under the high temperature might be due to 
the fact that the iron was then necessarily fractured at a 
stronger point than under the preceding low temperatures; 
but they compared, in all cases, the tensile strength obtained 
from the first trial under low temperatures with the tensile 
strength under the high temperature often after several 
fractures had been made under the low temperature and 
the weakest points thereby eliminated. 



INFLUENCE OF TEMPERATURE ON IRON. 147 

'•' The tenacity thus found under the high temperature, 
was of course, as much too great, comparatively, as the 
tenacity under the low temperature, for the number of 
fractures made, exceeded the tenacity at the first fracture 
under the low temperature. Yet, obvious as is this deduc- 
tion, the committee ignored it and attributed the entire 
increase of tenacity shown under the high temperature to 
the influence of that temperature alone, while, in fact, this 
increase was mainly, if not wholly, due to the elimination 
of the weakest points by the several previous fractures of 
the iron made under low temperatures. 

"As far as I am aware, this fact of the necessarily 
increasing tenacity of the iron at successive fractures, as a 
consequence of the continued elimination of weaker points 
by each preceding fracture, is now pointed out by me for 
the first time. The failure to perceive it caused Professor 
Walter R. Johnson to attribute an actual increase of 
strength conferred on the iron by the simple process of 
stretching, whereas this result was solely due to the removal 
of weak points. 

"Combining this error with that of the increase of 
strength assumed to be due to high temperatures, but really 
due to the same cause, led him to propose what he termed 
* thermo-tension ' treatment of iron as a means of increasing 
its tenacity. The whole principle of his process, however, 
being based on fallacious assumptions, its practical appli- 
cation proved worthless. 

"From a careful comparison of all the experiments I 
have been able to collect concerning the influence of tem- 
perature on the tenacity of wrought iron, the results show 
that between the temperatures of zero and 550° Fahren- 
heit, this influence is exactly nil, developing the important 
fact that between these limits no provision need be made 
by the engineer for effect of difference of temperature." 



CHAPTER VIII. 



STRENGTH OF BOILERS. 

Ultimate Strength — Factor of Safety— Safe Working Load — Strength 
of Riveted Shells — Collapsing Pressures — Strength of Welded 
Tubes — Stay Bolts and Braces — Steam Domes — Man Holes. 

The strength of a boiler will depend upon the material 
of which it is made ; the form and dimensions of its exte- 
rior and interior portions; the strength of intersecting 
joints, such as steam domes, nozzles, etc.; the strength of 
the riveted joints, and that of the system of stays which 
bind the portions of the whole together. 

The ultimate strength of a boiler is seldom or never 
called in question, except in connection with its safe work- 
ing pressure ; the former being necessary, however, to 
the determining of the latter. The strength of iron and 
steel plates, both single and double riveted, have already 
been given, but it yet remains to ^x upon the strength of 
riveted shells and flues in their actual form and dimensions 
before the w^orking pressure can be set with safety. The 
ultimate strength of a boiler is the greatest pressure which 
it. is capable of withstanding without danger of rupture. 
It is not necessary that the failure occur at the moment of 
over pressure, but whether it is likely to occur at all by 
a continued application. Experiments of this kind are 
both difficult and costly, and are therefore rarely made. 
Knowing the longitudinal and transverse strength of iron 
or steel plates, the strength of riveted joints, and in part, 
the many destructive influences which are at work and 
daily lessening the strength of the boiler, a certain frac- 



FACTOR OF SAFETY. 149 



tion of the ultimate strength, called a factor of safety, is 
selected as a basis of calculation at which boilers are con- 
sidered safe, after taking into account all the contingencies 
incident to boiler making and subsequent use (and, shall I 
say abuse?) in regular service. 

A factor of safety, in steam boilers, is a unit employed 
to show in what proportion a given pressure is less than 
the ultimate strength of the boiler. If a boiler is capable 
of withstanding an ultimate pressure of nine hundred 
pounds per square inch, and is used at a pressure of one 
hundred and fifty pounds, there is said to be a factor of 
safety of six with reference to the lower pressure, as com- 
pared with the ultimate strength. The numerical value 
given a factor of safety is the relation which it bears to 
the ultimate strength, and not that of the elastic limit; 
just what that figure should be for boilers has never been 
agreed upon, but has been narrowed down to either six 
or eight ; so that in ordinary boiler construction for land 
use, no very great discrepancies are likely to occur by the 
use of either in the regular course of business. In this 
country six is the ordinary factor of safety employed in all 
kinds of boiler work; in England it varies between six 
and eight. It is the practice among the best class of 
boiler makers in this country to make no boilers less than 
one-quarter inch thick, no matter if the factor of safety 
should reach ten or even twenty. This practice results 
mainly from the difficulty in calking the seams in the 
plates. 



150 



A TREATISE ON STEAM BOILEES. 



TABLE XLV. 

SHOWING THE TENSILE STRENGTH OF IRON AND STEEL PLATES, WITH 
SINGLE AND DOUBLE RIVETED JOINTS, AND THE SAFE WORKING 
STRENGTH PER SQUARE INCH OF SECTION, ALLOWING AS A FACTOR 
OF SAFETY ONE-SIXTH OF THE ULTIMATE STRENGTH. 





ULTIMATE STRENGTH OF 


SAFE WORKING LOAD OF RIVETED 


STRENGTH OF 


RIVETEE 


JOINTS. 


JOINTS 


PER SQUARE 


INCH. 


SOLID PLATE 

IN POUNDS PER 

SQUARE INCH. 


SINGLE 

RIVETED AT 

66 

PER CENT. 


DOUBLE 

RIVETED AT 

70 

PER CENT. 


SINGLE 
RIVETED. 


DOUBLE 
RIVETED. 


SOLID 
PLATE. 


45,000 


25,200 


31,500 


4,200 


5,250 


7,500 


50,000 


28,000 


35,000 


4,667 


5,833 


8,333 


55,000 


30,800 


38,500 


5,133 


6,417 


9,167 


60,000 


33,600 


42,000 


5,600 


7,000 


10,000 


65,000 


36,400 


45,500 


6,067 


7,583 


10,833 


70,000 


39,200 


49,000 


6,533 


8,167 


11,667 


75.000 


42,000 


52,500 


7,000 


8,750 


12,500 



The elastic limit of wrought iron is not far from one- 
half its tensile strength ; assuming it to be one-half, then the 
safe working load of solid plate as given in the above table 
has a factor of safety of only three as compared with the 
elastic limit. It is much easier to make tests for ultimate 
strength than for the limit of elasticity and the results are 
more definite ; it is for this reason, probably, more than any 
other, that the factor of safety is made referable to the 
ultimate, rather than the elastic strength of the material. 

If we had nothing to deal with other than the pressure 
necessary to tear the boiler shell asunder in the line of 
rivet holes, or in the line of its least strength, the problem 
of strength in design would be a very simple one. Unfor- 
tunately this is not the case. Every one at all convers- 
ant with the details of boiler construction knows that 



STRENGTH OF BOILERS. 151 

too many boilers are sent out with internal strains result- 
ing from bad workmanship, which no doubt in some cases 
will equal the intended working pressure. The efiect of 
these strains is to reduce the ultimate strength of the boiler 
and should always be taken into account. As there 
is no practical way of doing so we can only assume that 
a part of the. factor of safety is already expended. But in 
what proportion ? Perhaps no better answer can be given 
to this question than the data furnished in the following 
circular, issued by the English Board of Trade. 

The strength of boilers — The following circular, issued 
by the English Board of Trade, is for the information of 
engine and boiler makers, to enable them to know under 
what instructions the inspectors of the board of trade act 
in recommending the pressure of steam to be carried in 
boilers within their jurisdiction: 

*' When boilers are made of the best material, with all 
the rivet holes drilled in place and all the seams fitted with 
double butt straps of at least five-eighths the thickness of 
the plates they cover, and all the seams at least double-riv- 
eted with rivets having an allowance of not more than 
fifty per cent over the single shear, and provided that the 
boilers have been open to inspection during the whole period 
of construction, then six may be used as the factor of safety. 
But the boilers must be tested by hydraulic pressure to 
twice the working pressure in the presence and to the sat- 
isfaction of the board's surveyors. But when the above 
conditions are not complied with, the conditions in the 
following scale must be added to the factor six, according 
to the circumstances of each case : 



152 



A TREATISE ON STEAM BOILERS. 



A 


.15 


B 


.3 


C 


.3 


D 


.5 


E* 


.75 


F 


.1 


G 


.15 


H 


.15 


I 


.2 


J- 


.2 


K 


.2 


L 


.1 


M 


.3 


N 


.15 


O 


1. 


P 


.1 


Q 


.2 


R 


.1 


S 


.1 


T 


.2 


V 


.25 



X'' 



1.65 



To be added when all the holes are fair and good in the longitudinal seams, but 

drilled out of place after bending. 
To be added when all the holes are fair and good in the longitudinal seams, but 

drilled out of place before bending. 
To be added when all the holes are fair and good in the longitudinal seams, 

but punched after bending instead of drilled. 
To be added when all the holes are fair and good in the longitudinal seams, but 

punched before bending. 
To be added when all the holes are not fair and good in the longitudinal seams. 
To be added if the holes are all fair and good in the circumferential seams, but 

drilled out of place after bending. 
To be added if the holes are fair and good in the circumferential seams, but 

drilled before bending. 
To be added if the holes are fair and good in the circumferential seams, but 

punched after bending. 
To be added if the holes are fair and good in the circumferential seams, but 

punched before bending. 
To be added if the holes are not fair and good in the circumferential seams. 
To be added if double butt straps are not fitted to the longitudinal seams and 

the said seams are lap and double riveted. 
To be added if doable butt straps are not fitted to the longitudinal seams and 

the said seams are lap and treble riveted. 
To be added if only single butt straps are fitted to the longitudinal seams and 

the said seams are double riveted. 
To be added if only single butt straps are fitted to the longitudinal seams and 

the said seams are treble riveted. 
To be added when any description of joint in the longitudinal seams is single 

riveted. 
To be added if the circumferential seams are fitted with single butt straps and 

are double riveted. 
To be added if the circumferential seams are fitted with single butt straps and 

are single riveted. 
To be added if the circumferential seams are fitted with double butt straps and 

are single riveted. 
To be added if the circumferential seams are lap joints and are double riveted. 
To be added if the circumferential seams are lap joints and are single riveted. 
To be added when the circumferential seams are lap and the streaks or plates 

are not entirely under or over. 
To be added when the circumferential seams are not fitted with double butt 

straps and double riveted ; when the boiler is of such a length as to fire 

from both ends, or is of unusual length, such as flue boilers. 
To be added if the seams are not properly crossed. 

To be added when the iron is in any way doubtful and the surveyor is not sat- 
isfied that it is of the best quality. 
To be added if the boiler is not open to inspection during the whole period of 

its construction. 



Where marked * the allowances may be increased still further, if the workmanship 
or material is very doubtful or very unsatisfactory. 



The strength of the joints is found by the following 
method : 



STRENGTH OF BOILERS. 153 



(Pitch — diameter of rivets) X 100 f Percentage of strength of plate at 

— = < joint as compared with the solid 

Pitch. [ plate. 

(Area of rivets X No. of rows of rivets) X 100 f Percentage of strength of 

= i rivets, as compared with 

Pitch X thickness of plate. ( the solid plate.* 

" Then take iron as equal to twenty-three tons, and use 
the smallest of the two percentages as the strength of the 
joint, and adopt the factor of safety as found from the 
scale given in this circular : 



(51,520 X percentage of strength of joint) X twice 
the thickness of the plate in inches. 

Inside diameter of the boiler in inches X factor 
of safety. 



Pressure to be allowed 

I per square inch on 

the safety valves. 



"Plates that are. drilled in place must be taken apart 
and the burr taken ofi', and the holes slightly countersunk 
from the outsides. Butt straps must be cut from plates 
(and not from bars) and must be of as good a quality as 
the shell plates, and for the longitudinal seams must be 
cut across the fiber. The rivet holes may be punched or 
drilled out of place, but when drilled in place must be 
taken apart and the burr taken off and slightly counter- 
sunk from the outside. When single butt straps are used 
and the rivet holes in them punched, they must be one- 
eighth thicker than the plates they cover. The diameter 
of the rivets must not be less than the thickness of the 
plates of which the shell is made, but it will be found 
when the plates are thin, or when lap joints or single butt 
straps are adopted, that the diameter of the rivets should 
be in excess of the thickness of the plates^TnoMAS Gray." 

Strength of riveted shells — The bursting pressure of a 
cylinder of either wrought iron or steel may be estimated 
as follows: Multiply together the tensile strength of the 

* If the rivets are exposed to double shear, multiply the percentage as found by 1.5 



154 A TREATISE ON STEAM BOILERS. 

material in pounds per square inch and its thickness; 
divide this by the radius of the shell in inches, which will 
give the bursting pressure in pounds per square inch. By 
this rule a cylinder forty-eight inches diameter, one-quarter 
inch thick, of iron having a tensile strength of forty-five 
thousand pounds per square inch would yield, at a pressure 
of 468.75 pounds, as follows : 45.o_o^...2_5 ^ 468,75. 

This is true only of a continuous shell without any 
joint; as it is not practicable to construct such a boiler 
with our present appliances a deduction must be made for 
the seam of rivets. If single riveted the strength would 
be reduced to, say, fifty-six per cent of the above, which 
would lower the pressure to 262.5 pounds ; or if double 
riveted, to seventy per cent, which would ^x the bursting 
pressure at 328. pounds. The safe working pressure, 
allowing a factor of safety of six, would be ^6.|^j^ = 78.12 
pounds per square inch. 

It will be observed that the factor of safety does not 
take into account whether the shell is single or double 
riveted. As there is approximately twenty per cent difler- 
ence between the net results of the two percentages it is 
too large to be overlooked. It is customary to double 
rivet all longitudinal seams in boilers over forty -four inches 
in diameter, but not the circumferential seams. The stress 
on the end of a boiler is the area of the head multiplied 
into the pressure, and for the same shell as above would 
be, 48 X 48 X .7854 = 1809.6 square inches area. The sec- 
tional area of the metal in the shell = 48 X 3.1416 X .25 = 
37.7 square inches; this at 45,000 pounds per square inch 
would be capable of sustaining a load of 1,696,500 pounds 
before rupture ; or dividing this by the area thus, - floi y 
= 937.5 pounds necessary to produce transverse rup- 
ture, or twice that of the longitudinal seams. If the same 
reduction be made for riveted joints as in the preceding 
example then 937.5 X .56 = 525 pounds as the ultimate 



STRENGTH OF BOILERS. 



155 



strength to resist rupture, as against 262.5 pounds for a 
single riveted, or 328 pounds for double riveted longitu- 
dinal seams, which goes to show that nothing is to be 
gained by double riveting circumferential seams in ordi- 
nary cylindrical shells. 

If tubes or flues are inserted in the heads, their com- 
bined areas are to be deducted from the area of the head; 
this has the eflfect in many cases to reduce the pressure on 
the boiler heads more than one-half. 

The following tables, XLYI and XLYII, show the safe 
working pressure per square inch for iron or steel boilers, 
either single or double riveted : 



TABLE XLVI. 

SHOWING THE SAFE WORKING PRESSURE FOR SINGLE RIVETED IRON 
CYLINDER BOILERS, FROM TWENTY-FOUR TO SEVENTY-TWO INCHES 
IN DIAMETER, EMPLOYING A FACTOR OF SAFETY OF SIX. 





Single Riveted Iron Shells. 






DIAMETER 
OF 


THICKNESS 

OF 

SHELL. 


TENSILE STRENGTH 


PER SQUARE INCH. 


BOILER. 


40,000 


45,000 


50,000 


55,000 


24 


Y% inch. 


PRESSURE. 
104 


PRESSURE. 
117 


PRESSURE. 
130 


PRESSURE, 

143 




\ inch. 


139 


156 


174 


191 




-^ inch. 


174 


195 


217 


239 


26 


^ inch. 


96 


108 


120 


132 




\ inch. 


128 


144 


160 


176 




j\ inch. 


160 


180 


200 


220 


28 


-^ inch. 


89 


100 


112 


123 




\ inch. 


119 


134 


149 


164 




^ inch. 


149 


167 


186 


205 


30 


^ inch. 


83 


94 


104 . 


115 




\ inch. 


111 


125 


139 


153 




^ inch. 


139 


156 


174 


191 



156 



A TREATISE ON STEAM BOILERS. 



TABLE XL VI— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARi 


: INCH. 


OF 


OF 
SHELL. 










BOILER. 


40,000 


45,0C0 


50,000 


55,000 






PRESSURE. 


PRESSURE. 


PRESSURE. 


PRESSURE. 


32 


■^ inch. 


78 


88 


98 


107 




^ inch. 


91 


102 


114 


125 




■^ inch. 


130 


146 


163 


179 


34 


■^ inch. 


74 


83 


92 


101 




^ inch. 


98 


110 


123 . 


135 




^ inch. 


123 


138 


153 


169 


36 


■^ inch. 


69 


78 


87 


96 




^ inch. 


92 


104 


116 


127 




^ inch. 


116 


130 


145 


159 


38 


^ inch. 


66 


74 


82 


90 




1^ inch. 


88 


99 


110 


121 




^ inch. 


110 


123 


137 


151 


40 


T^ inch. 


63 


70 


78 


86 




^ inch. 


83 


94 


104 


115 




3^ inch. 


104 


117 


130 


143 


42 


3^ inch. 


60 


67 


74 


82 




^ inch. 


79 


89 


99 


109 




^ inch. 


99 


112 


124 


136 


44 


■^ inch. 


57 


64 


71 


78 




^ inch. 


76 


85 


95 


104 




^ inch. 


95 


107 


118 


130 


46 


^ inch. 


54 


61 


68 


75 




^ inch. 


72 


82 


91 


100 




TS inch. 


91 


102 


113 


125 


48 


y\ inch. 


52 


59 


65 


72 




^ inch. 


70 


78 


87 


96 



STRENGTH OF BOILERS. 



157 



TABLE XL VI— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 
SHELL. 










BOILER 


40,000 


45,000 


50,000 


55,000 






PRESSURE. 


PRESSURE. 


PRESSURE. 


PRESSURE. 


48 


3^ inch. 


87 


98 


109 


120 


50 


I inch. 


67 


75 


83 


92 




■^ inch. 


83 


94 


104 


115 




f inch. 


100 


112 


125 


138 


52 


I i-nch. 


64 


72 


80 


88 




■^ inch. 


80 


90 


100 


110 




f inch. 


96 


108 


120 


132 


54 


*i inch. 


62 


69 


77 


85 




^ inch. 


77 


87 


96 


106 




f inch. 


93 


104 


116 


127 


56 


^ inch. 


60 


67 


75 


82 • 




^ inch. 


75 


84 


93 


102 




f inch. 


89 


100 


112 


123 


58 


^ inch. 


57 


65 


72 


79 




^ inch. 


72 


81 


90 


99 




f inch. 


86 


97 


108 


119 


60 


^ inch. 


56 


63 


70 


77 




^ inch. 


70 


78 


87 


95 




f inch. 


83 


94 


104 


115 


66 


^ inch. 


51 


57 


63 


69 




^ inch. 


63 


71 


79 


87 




f inch. 


76 


85 


95 


104 


72 


1^ inch. 


46 


.52 . 


58 


64 




■^ inch. 


58 


65 


72 


80 




f inch. 


69 


78 


87 


96 



158 



A TREATISE ON STEAM BOILERS. 



The pressure given in the above and in the next tables 
for plates of 45,000 and 50,000 pounds tensile strength, 
agree closely with the best practice in this country for 
diameters ranging from thirty-six to forty-eight inches. 
Although single riveted seams may be strong enough for 
any pressure that may be required in any particular case, 
yet double riveting is to be recommended always, because 
the strength is increased thereby some twenty per cent; 
even then, it is thirty per cent below the strength of the 
solid plate. 

TABLE XLVII. 

SHOWfNG THE SAFE WORKING PRESSUEE FOR DOUBLE RIVETED IRON 
CYLINDER BOILERS, FROM TWENTY-FOUR TO SEVENTY-TWO INCHES 
DIAMETER, EMPLOYING A FACTOR OF SAFETY OF SIX AND ADVANC- 
ING THE PRODUCT TWENTY PER CENT FOR DOUBLE RIVETING. 

Double Riveted Iron Shells. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE INCH. 


OF 


OF 
SHELL. 










BOILER. 


40,000 


45,000 


50,000 


55,000 






PRESSURE. 


PRESSURE. 


PRESSURE. 


PRESSURE. 


24 


3^ inch. 


125 


140 


156 


172 




\ inch. 


167 


187 


209 


229 




-^ inch. 


209 


234 


260 


287 


26 


3^ inch. 


115 


130 


144 


158 




\ inch. 


155 


173 


192 


211 




3^ inch. 


192 


216 


240 


264 


28 


-^ inch. 


107 


120 


134 


148 




\ inch. 


143 


161 


179 


197 




1% inch. 


179 


200 


223 


246 


30 


^ inch. 


100 


113 


125 


138 




\ inch. 


133 


150 


167 


184 




Y% inch. 


157 


187 


209 


229 


32 


Y% inch. 


94 


106 


118 


128 



STRENGTH OF BOILERS. 



159 



TABLE XLVII— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 1 
SHELL. 










BOILER. 


40,000 


45,000 


50,000 


55,000 






PRESSURE, 


PRESSURE. 


PRESSURE. 


PRESSURE. 


32 


I inch. 


109 


122 


137 


150 




^g- inch. 


156 


175 


196 


215 


34 


-^Q inch. 


89 


100 


no 


121 




I inch. 


118 


132 


148 


162 




^ inch. 


148 


166 


184 


203 


36 


j^ inch. 


83 


94 


104 


115 




\ inch. 


110 


125 


139 


152 




fQ inch. 


139 


156 


174 


191 


38 


^ inch. 


79 


89 


98 


108 




I inch. 


106 


119 


132 


145 




^ inch. 


132 


148 


164 


181 


40 


3^ inch. 


76 


84 


94 


103 




I inch. 


100 


113 


125 


138 




^\ inch. 


125 


140 


156 


172 


42 


^ inch. 


72 


80 


89 


98 




J inch. 


95 


107 


119 


131 




3^ inch. 


119 


134 


149 


163 


44 


^ inch. 


68 


77 


85 


94 




i inch. 


91 


102 


114 


125 




3^ inch. 


114 


128 


142 


156 


46 


3^ inch. 


65 


73 


82 


90 




J inch. 


86 


98 


109 


120 




-^ inch. 


109 


122 


136 


150 


48 


^ inch. 


62 


71 


78 


86 




^ inch. 


84 


94 


104 


115 




^ inch. 


104 


118 


131 


144 



160 



A TREATISE ON STEAM BOILERS. 



TABLE XLVII— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 
SHELL. 








BOILER. 


40,000 


45,000 


50,000 


55,000 


50 


^ inch. 


PRESSURE. 

80 . 


PRESSURE. 
90 


PRESSURE. 
100 


PRESSURE. 

110 




^ inch. 


100 


.113 


.125 


138 




1 inch. 


. 120 


134 


150 


166 


52 


^ inch. 


77 


86 


96 


106 




^ inch. 


96 


108 


120 


132 




f inch. 


115 


130 


144 


158 


54 


^ inch. 


74 


83 


92 


102 




^ inch. 


92 


104 


115 


127 




f inch. 


112 


125 


• 139 


152 


56 


I inch. 


72 


80 


90 


98 




^ inch. 


90 


101 


112 


122 




1 inch. 


107 


120 


134 


148 


58 


I inch. 


68 


78 


86 


95 




j^ inch. 


86 


97 


108 


119 




f inch. 


103 


116 


130 


143 


60 


J inch. 


67 


76 


84 


-92 




^ inch. 


84 


94 


104 


114 




f inch. 


100 


113 


125 


138 


66 


I inch. 


61 


68 


76 


83 




^ inch. 


76 


85. 


95 


104 




f inch. 


91 


102 


114 


125 


72 


^ inch. 


55 


62 


70 


77 




3^ inch. 


70 


78 


86 


96 




f inch. 


83 


94 


104 


115 



STRENGTH OF BOILERS. 161 

In the tables following, the writer makes a distinction 
between ordinary iron boiler plate and what is called in 
the tables "high grade iron.'*' By this is meant flange iron, 
and what is sometimes called fire box iron; or in other 
words, the very highest grades of wrought iron plates, by 
whatever name they may be called. For ordinary shells 
made of C. H. No. 1 iron, 45,000 to 50,000 pounds is as 
high a tensile strength as it is safe to assume without test- 
ing; the 40,000 pounds iron is not recommended for any 
service in which high pressures are to be used. 

It is not probable that manufacturers will have frequent 
calls for iron boilers from 60,000 to 70,000 pounds tensile 
strength. Such irons are made, however, and could be 
furnished if ordered. There are western river steamboats 
which have boilers made of iron averaging not far from 
65,000 pounds tensile strength. If it is necessary to order 
this grade of iron for a boiler, samples should be cut from 
each sheet at the rolling mill, numbered or marked for test- 
ing before doing any work on the plate. If the samples (or 
coupons as they are generally called) do not come up to the 
required test the sheet is to be rejected. In the case of 
steel plates the tensile strengths should be chosen from 
60,000 to 65,000 pounds tensile strength, and ought not to 
exceed 70,000, and in no case more than 75,000 pounds. 
The ordinary temper and bending tests will suffice for steel 
of the three first grades; for the fourth or last, in addition 
to these, it should be tested for elongation and contraction 
of area. 



(12) 



162 



A TREATISE ON STEAM BOILERS. 



TABLE XLVIII. 

SHOWING THE SAFE WORKING PRESSURE FOR SINGLE RIVETED STEEL 
OR HIGH GRADE WROUGHT IRON CLYLINDER BOILERS, FROM TWENTY- 
FOUR TO SEVENTY-TWO INCHES IN DIAMETER, EMPLOYING A FAC- 
TOR OF SAFETY OF SIX. 

Single Riveted, Steel or Wrought Iron Shells. 



DIAMETER 

L OF 


THICKNESS. 
OF 


TENSILE STRENGTH 


PER SQUARE 


; INCH. 


BOILER. 


SHELL. 


60,000 


65,000 


70,000 


75,000 


""'' 24 


3 1 


inch. 


PRESSURE. 
156 


PRESSURE. 
169 


PRESSURE. 
182 


PRESSURE. 
195 




\ 1 


inch. 


208 


226 


243 


260 




5 


inch. 


260 


282 


304 


325 


26 


3 1 


inch. 


144 


156 


168 


180 




i ^ 


inch. 


192 


208 


224 


240 




A^ 


inch. 


240 


260 


280 


300 


28 


T6" ^ 


inch. 


134 


145 


156 


167 




i 


inch. 


179 


193 


208 


223 




5 


inch. 


223 


242 


260 


■ 279 


30 


1^^ 


inch. 


125 


135 


146 


156 




i 


inch. 


167 


181 


194 


,208 




T^ 


inch, 


208 


226 


243 


260 


32 


3 

TS" J 


inch. 


117 


127 


137 


147 




i ^ 


inch. 


156 


163 


182 


195 




5 1 
T6 J 


inch. 


195 


212 


228 


244 


34 


3 1 


inch. 


110 


119 


129 


138 




i 1 


inch. 


147 


159 


172 


184 




5 
T5^ 


inch. 


184 


199 


214 


230 


36 


^^ 


inch. 


104 


113 


122 


130 




i 


inch. 


139 


150 


162 


174 




3^g^ inch. 


174 


188 


203 


217 



STRENGTH OF BOILERS. 



163 



TABLE XLVIII— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 
SHELL. 










BOILER. 


60,000 


65,000 


70,000 


75,000 






PRESSURE. 


PRESSURE. 


PRESSURE. 


PRESSURE. 


38 


^^ inch. 


99 


107 


115. 


123 




I inch. 


132 


143 


154 


164 




-^ inch. 


164 


178 


192 


206 


40. 


^ inch. 


94 


101 


109 


117 




1 inch. 


125 


135 


145 


156 




-^^ inch. 


156 


169 


182 


195 


42 


y^6 inch. 


89 


97 


104 


112 




I inch. 


119 


129 


139 


149 




3^ inch. 


149 


161 


174 


186 


44 


^ inch. 


85 


92 


99 


107 




I inch. 


114 


123 


133 


142 




^ inch. 


142 


154 


166 


178 


46 


A inch. 


82 


88 


95 


102 




^ inch. 


109 


118 


127 


136 




^ inch. 


136 


147 


159 


170 


48 


Y^g inch. 


78 


84 


91 


97 




^ inch. 


104 


113 


121 


130 




^g^ inch. 


130 


141 


152 


162 


50 


\ inch. 


100 


108 


116 


124 




^ inch. 


124 


J 35 


145 


156 




f inch. 


150 


162 


175 


188 


52 


I inch. 


96 


104 


112 


120 




■]^ inch. 


120 


130 


140 


150 




1 inch. 


144 


156 


168 


180 



164 



A TREATISE ON STEAM BOILERS. 



TABLE XLVIII— Continued. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 
SHELL. 










BOILER. 


60,000 


65,000 


70,000 


75,000 


54 


i ^ 


inch. 


PRESSURE 
93 


PRESSURE. 
100 


PRESSURE. 
108 


PRESSURE. 
116 




T^6 


inch. 


136 


3 25 


135 


145 




1 


inch. 


139 


150 


162 


174 


56 


i i 


nch. 


89 


96 


104 


111 




5 
Tl" 


inch. 


111 


121 


130 


140 




3 

8 


inch. 


134 


145 


156 


167 


58 


i ^ 


inch. 


86 


93 


100 


108 




^ 


inch. 


108 


117 


126 


135 




1 


inch. 


129 


140 


151 


162 


60 


1 1 
4- J 


inch. 


83 


90 


97 


104 




5 
16 


inch. 


104 


113 


121 


130 




1 


inch. 


125 


135 


146 


156 


66 


4 J 


nch. 


76 


82 


88 


95 




5 


inch. 


95 


103 


110 


1J8 




1 


inch. 


J 14 


123 


133 


142 


72 


i- 1 


inch. 


69 


75 


81 


87 




5 
T6 


inch. 


87 


94 


101 


108 




f inch. 


104 


113 


122 


130 



A word of caution may not be out of place just here in 
regard to using thinner plates of steel because of its 
higher tensile strength; for example: the substituting of a 
42 X 3^ X 70,000 lbs. shell made of steel, instead of a 42 X i 
X 50,000 lbs. shell made of iron would not be recommended 
by any boiler maker who cared anything for his reputation, 
and the reasons are quite obvious, the principal one being 



STRENGTH OF BOILERS. 



165 



that the tightness of a riveted joint is not increased because 
of the increased tensile strength of the plates, and it would 
be a very difficult matter to keep such a boiler tight, espe- 
cially if of considerable length. The writer does not favor 
the use of plates less than one-quarter inch thick for boil- 
ers when exceeding thirty inches in diameter, whether of 
steel or iron ; neither does he recommend single riveting 
for boilers of any diameter when constructed of steel or 
of iron having these high tensile strengths. 



TABLE XLIX. 

SHOWING THE SAFE WORKING PBESSURE FOR DOUBLE RIVETED STEEL 
OR HIGH GRADE IRON CYLINDER BOILERS, FROM TWENTY-FOUR TO 
SEVENTY-TWO INCHES DIAMETER. EMPLOYING A FACTOR OF 
SAFETY OF SIX, AND ADVANCING THE PRODUCT TWENTY PER CENT 
FOR DOUBLE RIVETING. 

Double Riveted Iron or Steel Shells. 



DIAMETER 


THICKNESS 


TENSILE STRENGTH 


PER SQUARE 


INCH. 


OF 


OF 
SHELL. 










BOILER, 


60,000 


65,000 


70,000 


75,000 






PRESSURE. 


PRESSURE. 


PRESSURE. 


PRESSURE. 


24 


^ inch. 


187 


203 


218 


234 




^ inch. 


250 


271 


292 


312 




^ inch. 


312 


338 


365 


390 


26 


^ inch. 


173 


187 


202 


216 




I inch. 


230 


250 


269 


288 




^^ inch. 


288 


312 


336 


360 


28 


j\ inch. 


161 


174 


187 


200 




]- inch. 


215 


232 


250 


268 




Y^e inch. 


268 


290 


312 


335 


30 


^ inch. 


150 


162 


175 


187 




\ inch. 


200 


217 


233 


250 




3^ inch. 


250 


271 


292 


312 



166 



A TREATISE ON STEAM BOILERS. 



TABLE XLIX— Continued. 



DIAMETER 
OF 


THICKNESS 

OF 

SHELL. 


TENSILE STRENGTH 


PER SQUARE INCH. 


BOILER. 


60,000 


65,000 


70,000 


75,000 


32 


x% inch. 


PRESSURE. 
140 


PRESSURE. 

152 


PRESSURE. 

164 


PRESSURE. 
176 




i inch. 


187 


196 


218 


234 




^ inch. 


234 


254 


274 


293 


34 


^ inch. 


132 


143 


155 


166 




i inch. 


176 


191 


206 


221 




^^ inch. 


221 


239 


257 


276 


36 


^ inch. 


125 


136 


146 


156 




^ inch. 


167 


180 


194 


209 




^ inch. 


209 


226 


244 


260 


38 


x% inch. 


119 


128 


138 


148 




i inch. 


158 


172 


185 


197 




y5^ inch. 


197 


214 


230 


247 


40 


T%inch 


113 


]21 


131 


140 




i inch. 


150 


162 


174 


187 




^ inch. 


187 


203 


218 


234 . 


42 


3^ inch. 


107 


116 


125 


134 




i inch. 


143 


155 


167 


179 




^ inch. 


179 


193 


209 


223 


44 


T^ inch. 


102 


110 


119 


128 




I inch. 


137 


148 


160 


170 




^ inch. 


170 


185 


199 


214 


46 


^^ inch. 


98 


106 


114 


122 




J inch. 


131 


142 


152 


163 




T^ inch. 


163 


176 


191 


204 


48 


3^ inch. 


94 


101 


109 


116 



STKENGTH OF BOILERS. 



167 



TABLE XLIX— Continued. 



DIAMETER 
OF 


THICKNESS 

OF 

SHELL. 


TENSILE STRENGTH 


PER SQUARE INCH. 


BOILER. 


60,000 


65,000 


70,000 


75,000 


48 


I inch. 


PRESSURE. 

125 


PRESSURE, 
136 


PRESSURE. 

145 


PRESSURE. 
156 




-fQ inch. 


156 


169 


182 


194 


50 


^ inch. 


120 


130 


139 


149 




^ inch. 


- 149 


162 


174 


187 




1 inch. 


180 


194 


210 


226 


52 


I inch. 


115 


125 


134 


144 




-^ inch. 


144 


156 


168 


180 




f inch. 


173 


187 


202 


216 


54 


I inch. 


112 


120 


130 


139 




-^ inch. 


139 


150 


162 


174 




1 inch. 


167 


180 


194 


209 


56 


I inch. 


107 


115 


125 


133 




-^ inch. 


133 


145 


156 


168 




f inch. 


161 


174 


187 


200 


58 


I inch. 


103 


112 


120 


130 




-^ inch. 


130 


140 


151 


162 




1 inch. 


155 


168 


181 


194 


60 


I inch. 


100 


108 


116 


125 




^ inch. 


125 


136 


145 


156 




f inch. 


150 


162 


175 


187 


66 


I inch. 


91 


98 


106 


114 




^ inch. 


114 


124 


132 


142 




1 inch. 


137 


148 


160 


170 


72 


1^ inch. 


83 


90 


97 


104 




^ inch. 


104 


113 


121 


130 




f inch. 


125 


136 


146 


156 



168 A TREATISE ON STEAM BOILERS. 

Collapsing pressures — The best experimental data rela- 
ting to the collapsing pressures for flues or tubes are those 
of Sir William Fairbairn. The pressure necessary to col- 
lapse a flue was found to vary nearly according to the fol- 
lowing laws : 

Inversely as the length. 

Inversely as the diameter. 

Inversely as a function of the thickness, which is nearly 
the power whose index is 2.19 ; but which for ordinary 
practical purposes may be treated as sensibly equal to the 
square of the thickness. 

By these formulas the 2.19 power of the thickness 
multiplied by 806,300, and divided by the product of diame- 
ter in inches by the length in feet, is undoubtedly correct 
for thin flues of certain lengths. The 2 power of the 
thickness is also correct for another class of thicker flues. 
In the following tables both of these formulas are used — 
the 2.19 in the right hand triangle, and the 2 in the left, 
i^either of these formulas appear to apply to heavy flues 
of great lengths. This, to a certain extent, is on account 
of the laps acting upon the principle of Fairbairn's bands. 

In the tables of internal pressure, one-fifth of the value 
of ordinary boiler iron (say 50,000 pounds to the inch of 
section) is taken to be safe; while in the external one-third 
is taken; this is on account of the great variation in the 
tensile strength of iron. 

Note — Headings to Tables L and LI sliould read, ''Showing Safe 
Working Pressures against Co//ap,sg,". according to Fairbairn'.s .for-niula, etc. 



COLLAPSING PRESSURES. 



169 





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170 



A TREATISE ON STEAM BOILERS. 






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COLLAPSING PRESSURES. 171 

The pressures aloQg the diagonal space show the efiect 
of these two formulas on the same diameter, length and 
thickness ; also, the comparative strength of thick and 
thin flues of the same length and different diameters, viz^ 
a flue thirty-six inches in diameter, three-eighths thick, ten 
feet long, is about as strong as one seven inches diameter,. 
.165 inches thick, of the same length. 

The resistance to collapse depends very much on the 
flues being exactly cylindrical, and it is for this reason that 
all large tubes intended for internally fired boilers should 
be fitted with butt riveted, instead of lap riveted joints. 
Mr. Fairbairn found that the fines were greatly strength- 
ened by riveting angle or T iron rings at regular distances 
on the fines; and as the collapsing resistance is very much 
less than the safe working internal pressure, these rings 
should be applied until the bursting and collapsing press- 
ures equaled each other. Whenever practicable, the thick- 
ness of metal in the flue and in the shell ought to be the 
same. In very large boilers this can not be done. Instead 
of the rings spoken of above, it is now" the practice of 
many boiler makers to use welded flues in short lengths ; 
flanging the ends, and then riveting together in much the 
same way that flanged cast iron pipes are bolted. 

In regard to small tubes, the following table may often 
be found useful. It is taken trom D. K. Clark's Manual 
of Rules, Tables and Data : 



172 



A TREATISE ON STEAM BOILERS. 



TABLE LII. 

SOLID DRAWN IRON TUBES— CALCULATED BURSTING AND COLLAPSING 

PRESSURES. 



EXTER- 


THICKNESS. 


INTER- 


BURSTING PRESSURE. 


COLLAPSING 
PRESSURE. 


NAL 






NAL 


PER SQ. IN. 


PER SQ. 


PER SQ. 


PER SQ. 


DIAME- 
TER. 


B.W.G 


INCH. 


DIAME- 
TER. 


OF 
INTERNAL 


INCH OF 
SECTION 


INCH OF 

ext'rnal 


INCH OF 
SECTION 










SURFACE. 


OF METAL 


SURFACE. 


OF METAL 


INCHES 






INCHES. 


POUNDS. 


TONS. 


POUNDS. 


TONS. 


li 


14 


.083 


1.084 


7,700 


22.4 


6,500 


21.7 


If 


14 


.083 


1.209 


6,900 


22.4 


5,800 


21.3 


n 


14 


.083 


1.334 


6,200 


22.4 


5,200 


21.0 


ii 


14 


.083 


1.459 


5,700 


22.4 


4,700 


20.7 


If 


14 


.083 


1.584 


5,300 


22.4 


4,300 


20.3 


n 


14 


. .083 


1.709 


4,900 


22.4 


4,000 


20.0 


2 


14 


.083 


1.834 


4,500 


22.4 


3,700 


19.7 


2i 


13 


.095 


1.935 


4,900 


22.4 


3,800 


19.3 


n 


13 


.095 


2.060 


4,600 


22.4 


3,600 


19.0 


2J 


12 


.109 


2.282 


4,800 


22 4 


3,600 


18.3 


03 

■"4 


12 


.109 


2.532 


4,300 


22.4 


3,100 


17.7 


3 


11 


.120 


2.760 


4,400 


22.4 


3,000 


17.0 


H 


11 


.120 


3.010 


4,000 


22.4 


2,700 


16.3 


H 


10 


.134 


3.232 


4,200 


22.4 


2.700 


15.7 


3f 


10 


.134 


3.482 


3,900 


22.4 


2,400 


15.0 


4 


10 


.134 


3.732 


3,600 


22.4 


2,100 


14.3 


4i 


10 


.134 


3.982 


3,400 


22.4 


1,900 


13.7 


M 


10 


.134 


4.232 


3.200 


22.4 


1,700 


13.0 


43 

^4 


10 


.134 


4.482 


3,000 


22.4 


1.600 


12.3 





10 


.134 


4.732 


2,800 


22.4 


1,400 


11.7 


^1 


9 


.148 


5.204 


2,800 


22.4 


1,200 


10.3 


6 


9 


.148 


5.704 


2,600 


22.4 


1,000 


9.0 



Stay bolts — The sides of locomotive and portable engine 
fire boxes have a greater or less extent of fiat surface, sub- 



STAY BOLTS. 173 



ject to both external and internal pressures. These sur- 
faces are opposite each other, and are kept in place by 
screwed stays, riveted over the ends. Each of these bolts 
or stays sustains the pressure of steam against a certain 
area of the plate to v^hich they are attached. In some 
tests made by Mr. Fairbairn on three-quarter inch iron 
stay bolts with enlarged ends screwed into an iron plate 
three-eighths inch thick, and then riveted over, it was 
found that such a stay would resist 30,000 pounds breaking 
weight. If we allow a factor of safety of six this would 
give 5,000 pounds as the safe load on a single stay for the 
diameter and thickness of plate, as given above. 

In tests of stayed ends similar to those of fire boxes 
for portable engines, Messrs. Greig and Eyth experimented 
on three drums, in which one end plate, representing the 
inside of the fire box was of three-eighths inch plate ; the 
other, corresponding to the outside shell, was nine-six- 
teenths inch. This greater thickness was not required by 
the boiler as such, but is employed in the special case of 
steam plowing or traction engine boilers where this side 
plate carries part of the machinery. 

The stays were seven-eighths inch in diameter, four 
and a quarter inches apart, and in drums 'Nos. 1 and 2 
were riveted over the ends on both sides. They were 
tapped right through, having fourteen threads per inch. 
One of these drums (1) was entirely of steel, the other (2) 
of iron. The third drum was of steel, with check nuts on 
the end of the stays on the side of the weaker plate. The 
clear space between the two plates was two and a half 
inches wide, exactly corresponding to the water space of 
the fire box. 

The iron barrel (^o. 2) failed with a pressure of 1,230 
pounds per square inch. In this case one of the outside 
stays gave way; the first signs of the failure appeared with 
a pressure of about 1,150 pounds, when the edges of the 



174 A TREATISE ON STEAM BOILERS. 

rivet head of the stay crumbled away. The plate bulg- 
ing out between the stays, the one which failed slipped 
gradually and noiselessly through the hole of the thin- 
ner plate, through which the water then escaped. The sec- 
tion of the solid part of the stay (minus the thread) 
having a diameter of barely ^ inch, is 0.51 square inch* 
The tensile strength of the iron employed was 22.23 tons 
per square inch, and a stay ought therefore to carry 11.34 
tons, or 25,400 pounds. The area supported by the stay 
should have been 4j inches square, or 18.06 square inches. 
In this case the riveted head of the stay gave way at 
twelve per cent below its regular breaking strain. 

The steel drum (IS'o. 1) broke'under a pressure of 1,628 
pounds per square inch. In this case a stay broke fairly 
in the middle between the two plates with a loud report, 
the plates bulging out freely. In this case, as before, the 
area supported by one stay is 16.06 square inches, so that 
the maximum pressure put on one stay amounted to 
29,402 pounds. The sectional area is as before, 0.52 square 
inch, and the breaking strain of the steel employed is 
64,579 pounds per square inch. The stay ought therefore 
to be able to carry 33,581 pounds, but as it carried only 
29,402 pounds, it broke with a strain twelve per cent less 
than its maximum tensile strength. 

The experiment with the stays provided with nuts was 
a failure ; but there is no doubt that the tendency to bulge is 
considerably checked by nuts. Many locomotive builders 
are now using them on the projecting ends of stay bolts 
and the practice seems to be growing in favor in Europe 
rather than in this country. 

The usual practice of staying flat crown sheets is by 
means of crown bars and bolts, which is, all things con- 
sidered, a very objectionable method of staying, owing 
to the accumulation, of deposit underneath and between 
the bars. A much better way is to use round stays 



STAY BOLTS. 



175 



screwed into the crown sheet and riveted over, or fitted 
with nuts. 

The diameter of stay bolts is usually three times the 
thickness of the plates for one-quarter and five-sixteenths 
inch plates, and from two to two and a quarter diameters 
for half inch and five-eighth plates. They are arranged in 
vertical rows at a distance of four to four and a half inch 
centers in the best locomotive practice. In portable en- 
gines where the pressures are much lower, say about one- 
half less, they are usually placed at from four and a half, to 
five inch centers, depending on the thickness of the metal. 
It is not customarv to take into account the tensile strenofth 
of the plates composing the shell or fire box, as the whole 
pressure is assumed to be upon the stay bolts. 

TABLE LIII. 

GIVING PROPORTIONS FOR STAY BOLTS FOR FLAT SURFACES- 





CENTER TO CENTER OF STAY BOLTS, IN INCHES.' 


PRESSURE 












PER 


I IN. PLATE. 


3^ IN. PLATE 


f IN. PLATE. 


y^^ IN. PLATE 


i IN. PLATE. 


SQ. INCH. 












f IN. STAY. 


f IN. STAY. 


f IN. STAY. 


1 IN. STAY. 


IJiN. STAT. 


50 


6 


7 


8 


9 


10 


60 


5f 


6f 


H 


8* 


9 


70 


5 


5f 


6| 


n- 


8f 


80 


4| 


5J 


H 


n 


71 


90 


^ 


5i 


5i 


6| 


73 
' 8 


100 


H 


4f 


^ 


6i 


7 


no 


4 


^ 


H 


5| 


H 


120 


H 


4i 


5 


5f 


6| 


130 


3f 


4i 


4| 


5i 


6^ 


140 


H 


H 


4f 


5i 


6 


150 


^ 


4 


^ 


5 


5| 



176 A TREATISE ON STEAM BOILERS. 

The preceding table gives the results of a comparison 
of several formulas and dimensions taken from the best 
practice, and thus fixing the average proportions for diam- 
eter of stays based on the thickness of metal and distance 
apart from center to center for pressure, as given in the 
first column. It will be understood that this table is 
empirical and varies only from the well known formula 

s = ,/4oooxA by taking into account the stiffness of the plates 

p 
between supports. 

In staying boiler heads, it is the usual practice to rivet 
an angle or T iron to the head, and attach stay rods or 
braces running from this piece to some part of the shell or 
through to the other end of the boiler. There should be 
some arrangement by which these stay rods may be 
brought into tension ; a link and key is perhaps as good as 
any, and almost anything is better than a screw, as the 
threads are apt to waste away if in the steam space, and 
to be covered with scale if in the water space, so as to prac- 
tically render them useless after the first application, before 
cleaning, should it be necessary to remove them for clean- 
ing. The size of the stay rods may be determined by first 
fixing upon the number that are to be used; the area under 
pressure to be supported, divided by the number of stays, 
will give the load upon each, l^o stay rod should have a 
load upon it greater than 4,000 pounds per square inch. 
Thus the diameters of the stay rods may be easily arrived at. 

As has been already said, the area taken up by the 
tubes or fines in the boiler heads reduces the total pressure 
on the heads by just that amount. Large flues are always 
riveted to the heads, and thus act as stays. Sometimes 
both the heads are flanged, as shown in figure 33, on page 
141, in which.case the fines are simply straight cylinders; at 
other times one head only is flanged in this manner, the 



EXPANDING TUBES. 177 



other head beiag cat oat to receive the flae, which has a 
flanged ead not unlike that on a cast iron pipe ; this flange 
on the flue is broaght up against the head and both riveted 
together, the other end of the flue being riveted as described 
above. Tubes less than ^ve inches diameter are expanded 
by special tools into plain smooth holes bored out in the 
heads; these also act, in a less degree, however, as stays by 
the slight "bead" or riveting over of the tubes on the 
outside of the heads. 

The Prosser tube expander, as in general use, is shown 
in elevation in figure 34. It consists of a number of steel 




Figure 34. 



pieces with radial joints, the whole being so arranged that 
the tool may be inserted in the tube, and by driving on the 
end of the tapered steel pin passing through the center of 
these steel pieces, they are forced out radially, and thus by 
successive operations stretch the end of the tube until it 
accurately fills the hole. The expander is made partially 
concave near the end, the length of this groove approxi- 
mating the thickness of the head and about three times the 
thickness of the tube. Tubes put in by this method being 
expanded on both sides of the tube plate in one operation, 
serve as braces and tend greatly to stifl'en the head. Before 
the tubes are put in place they should be carefully cut to 
length before expanding, as the chipping off the end of the 
tube in place is not only unworkmanlike, but there is 
. (13) 



178 



A TREATISE ON STEAM BOILERS. 



danger of splitting the tube. It sometimes happens, that 
the heads are not perfectly flat, and the inside tubes 

will require to be somewhat shorter 
than those nearer the flanged edge. 
For this another tool is made, and is 
well adapted for the purpose, figure 36 
being a sectional elevation, figure 35 a 
perspective view of the ring for shear- 
ing the tube, and figure 37 a represent- 
FiGURE 35. ation of the expander complete. 

The patent combined tube expander and cutter consists 
of a Prosser expander, the outside bead of which has a 
cutting edge, also a collar with cutting edges inside. The 
two cutting edges act as a shear, making a clean sq^uare 





cut from end of tube. This method of cutting off" ends ot 
tubes will be found to be a great improvement over the 
usual practice of cutting them off" with a chisel. ■ 

To expand and cut off a tube, the collar is placed over 
the end of the tube and against the tube plate a. The 
expander and cutter is then inserted within the tube until 
the gauges J, which are shown as shoulders on the seg- 
ments, meet the end of the collar, in which position the 



TUBE EXPANDERS. 



179 



cutting edges i are in proper position with reference to the 
cutting edge of the collar. When in this position the taper- 




FlGURE 73. 



ing mandrel is driven in and from time to time rotated until 
a suitable portion of the end of the projecting tube is cut off 
and the tube at the plate is properly expanded. About 
one-eighth of an inch of the tube end is left projecting 
beyond the plate a, and the piece cut off is left within the 
collar. When the collar and tube are removed, the pro- 
jecting end is properly calked against the plate. 

The calking tool em- 
ployed in finishing the ends 
of the tubes is shown in 

figui'e 38. p,^^^^ 33 

Dudgeon's roller tube expander is shown in figure 39, 
and is designed to properly expand the tube by means of a 
continuous rotary pressure, and thus lessen the liability of 
splitting the tubes by driving in a conical or other expand- 





FlGURE 39. 



ing device. Tubes can be expanded without striking a 
blow on them, thus rendering them far less liable to crack. 
Leaky ones can be tightened, with steam on the boiler, 



180 A TREATISE ON STEAM BOILERS. 

with perfect safety. One expander will answer for any 
thickness of tube sheet, thus avoiding the necessity of an 
expander for each different thickness of sheet. They are 
DO more liable to break than the common tool, and are 
easily kept in order, as the rollers are the only things that 
can give out, and they can be replaced in a few moments 
by unscrewing the cap, B. 

Steam domes — The strength of boilers is often lessened 
by cutting out large holes in the shell for steam domes. 
What particular function this appendage plays in ordinary 
stationary boilers, would be hard to divine on any economic 
grounds. The writer confesses to having put hundreds of 
them on boilers in which they served no more useful pur- 
pose than if they had been placed on the steam chest of 
the engine instead. It sometimes happens that commer- 
cial requirements come in conflict with the judgment of 
the engineer, and, as is too often the case, the latter has to 
submit to the former. A steam dome is just such a case 
in point. 

The common argument in favor of a steam dome is that 
it increases the steam room of the boiler. Suppose it 
does; why the necessity of this increase? If the boiler 
shell is too small, then an increase of steam room might 
under some conditions be a good thing; but whether it 
will increase the efficiency of the boiler by a better circu- 
lation of water, or, by a freer liberation of the steam in 
the water, ought, but seldom is taken into account. If 
what a steam dome costs were put into a larger shell, leav- 
ing the arrangement, size and number of tubes or flues 
the same, it would be a positive gain in strength not only, 
but in economy. 

The shell of the boiler is weakened in the first place, 
by cutting out a large hole over which the dome is to be 
placed. In a very large percentage of cases this hole is 



STEAM DOMES. 181 



ten times larger in area than there is any necessity for. 
Why a hole sixteen inches in diameter should be cut in 
the shell of a boiler and leading into a dome which would 
not hold half a barrel, and then attaching a three inch 
pipe to conduct the steam to the engine, is probably beyond 
the boundary of satisfactory explanation. This is in itself 
bad enough, but in the second place, in addition to this 
there is a row of rivet holes, usually two and a half to 
three inches in diameter larger than the dome, thus still 
further weakening the metal around the hole. 

Some establishments have special drilling machines for 
drilling these holes ; this is the exception rather than the 
rule. The usual way is to flange the dome and fit it to the 
shell; the dome is then drilled and the shell marked from 
these holes. The dome being removed, the holes are cut 
through the shell with a chisel, then reamed, drifted or 
chipped, so as to allow the rivet to enter. In fibrous iron 
it is not an infrequent occurrence to split the plates around 
the holes. The lower lamina of the plate is almost sure to 
be loosened or driven into the interior of the boiler. If 
there is anything within the whole range of mal-treatment 
to which boilers are subjected which at all approaches the 
average fitting a dome to a shell, the writer has failed to 
detect it. 

If a dome must be put on a boiler in order to make a 
sale, the hole leading from the shell into the dome ought 
not to greatly exceed twice the area of the pipe leading to 
the engine. Figure 40 shows the idea 
clearly. This has been the practice of 
the writer, and has never, to his knowl- 
edge, given any trouble. A small hole 
should be cut through the shell on each ^^^^^^^^^^| 
side, at a point just inside of the sides figure 40. 

of the dome, to drain any water of condensation which 
might collect there back into the boiler. 



182 



A TREATISE ON STEAM BOILERS. 



If a dome must be put on a boiler, it ought to be of 
such a size as to appear well in proportion to the whole. 
The diameter of the boiler naturally suggests itself as that 
portion by which to fix the diameter of the dome. The 
following table gives the sizes generally used by the Writer, 
when no particular size is included in the contract ; the 
thickness of the metal in the dome sheet being one-quarter 
inch at the top and five-sixteenths of an inch at the bottom. 
These sheets are rolled thicker at the bottom to give more 
metal where the flange is to be formed. 

TABLE "LIV. 

PROPORTIONS FOR STEAM DOMES. 



DIAMETER OF 


SIZE OF DOME. 


DIAMETER 
OF BOILER. 


SIZE OF DOME. 


BOILER 


DIAMETER. 


HEIGHT. 


DIAMETER. 


HEIGHT. 


INCHES. 


INCHES. 


INCHES. 


INCHES. 


INCHES. 


INCHES. 


24 


12 


15 


44 


26 


26 


26 


13 


16 


46 


28 


26 


28 


15 


17 


48 


28 


28 


30 


16 


18 


50 


30 


30 


32 . 


18 


20 


52 


32 


32 


34 


18 


20 


54 


32 


32 


36 


20 


22 


56 


34 


34 


38 


22 


22 


58 


34 


34 


40 


24 


24 


60 


36 


36 


42 


24 


24 









STEAM DRUMS, 



ISb 



A steam drum, as 
shown in figure 41, is to 
be preferred to a dome 
riveted to the shell; the 
opening in the boiler is 
less, there are fewer rivet 
holes and these are con- 
fined to a smaller diam- 
eter. The interior diam- 
eter of the nozzles may 
be, for boilers from 



Jliiniii'iiiiiiniir 




riiiiiiniiilini 

Figurp: 41. 



24 to 44 inches diameter '. 4 inches. 

46 to 50 inches diameter. 5 inches. 

52 to 60 inches diameter 6 inches. 

The metal in the nozzles should be about an inch 
thick, not for strength to resist the pressure of steam, but 
the better to withstand the eftects of rough handling, etc. 
The diameters of the drums for any given boiler may be 
the same as given in table LIV for domes, and in length 
they may be two diameters, to look well. 




iiHiiiiiiiii hiiMMnn i 



lliiiiiiiiiiiiiiiiiniiinil 



FiGURK 42. 



If a boiler really needs more steam room, then a drum 
should be of sufficient size to make it a useful appendage. 
In such a case, a drum as shown in figure 42 is recom- 
mended. 



184 



A TREATISE ON STEAM BOILERS. 



In reg'ard to size, it may be half the diameter and not 
less than half the length of the boiler to which it is to be 
applied. It should be placed midway on the boiler, and 
have the nozzles connecting the drum with the interior of 
the boiler, as shown. 




Figure 43. 



Man holes, when cut into the circumferential part of the 
boiler, are a source of weakness. A man hole should never 
be placed there, if it is possible to get it into either head. 
In any ordinary flue or tubular boiler -it can be placed 

in the head, as shown in figure 
43, without interfering with any- 
thing about the boiler, either 
externally or internally. "When 
man holes are placed in the 
heads, there should be one below 
the tubes or flues, if possible, and one above them. This will 
in most cases allow ample facility for cleaning or repairs. 
There should be in all cases a heavy wrought iron ring 
riveted around the hole. Many boiler makers neglect this 
altogether, and many who do put in such a ring make it 
so light as to be of little or no service in strengthening the 
head. The writer has seen rings around man holes in 
which the net sectional area of the ring through the center 
of any given hole was scarcely more than the area of metal 
punched out of the head, for the insertion of a rivet by 
which it was to be attached to the head. This is all wrong, 
and the boiler would lose little or nothing in strength if 
the ring were left off" altogether. 

When it is impracticable to put the man holes in the 
heads, then the shell should be strengthened by a heavy 
ring, which may be riveted to the inside of the boiler and 
the man hole plate make its joint on the ring itself. A 
very common practice is to make a cast iron " saddle,'^ 
with a flange to fit the boiler, and a portion of the casting 



MAN HOLES. 



185 



carried up high enough to make a flat joiut foi" the man 
hole plate on its inner side. Such a device needs to be 
recommended with some caution. A cast iron fitting 
around a hole, say ten by sixteen inches, in the shell of a 
boiler, while it may not be dangerous, should not be 
accepted as perfectly safe. The following engraving, figure 
4Si, represents a form of 
exterior wrought iron fit- 
ting for man holes, by W. 
& J. Gallowav, Manches- 
ter, England. This is an 
excellent device for the 
purpose, and one which 
it would be well to adopt 
in this country. It is pos- 
sible that wrought iron 
rings are so applied in this country, but the writer has not 
seen them. 

Sometimes a steam dome is fitted with a cast iron head 
and the man hole plate is fitted in it. In such a case 
the opening into the dome from the interior of the boiler 
should have a heavy wrought iron ring, as already described 
in a preceding paragraph. 




Figure 433^. 



CHAPTER IX. 



HEATING SURFACE AND BOILER POWER. 

Transfer of Heat — Radiation — Conduction — Convection — Heating Sur- 
face, Internal, External — Position of Heating Surface — Heating 
Surface of Tubes and Flues — Evaporation as Modified by Heating 
Surface, in Kind and Extent — Relation of Grate Area to Heating 
Surface — Evaporation Modified by the Circulation of Water in the 
Boiler — Boiler Power — Evaporative Capacity and Economy — EflSi- 
ciency of a Boiler — Rating of Boiler Power. 

Transfer of heat — This is accomplished by radiation, 
conduction, convection. Radiation, considered as a mode 
of transference of heat, is a process which can only go on 
between at least two material bodies, one of which gives 
out, and the other receives heat. The phenomena of radi- 
ant heat have been studied, and its laws well ascertained, 
and, as a luminous body sends out rays of light in all 
directions, in straight lines, so also does a heated body 
send out rays of heat in all directions, in straight lines. 
These rays of heat, like those of light, may be reflected and 
refracted, and seem in all respects to be identical, with the 
exception that the former is known to us only through the 
sensation of feeling, or are measurable by means of a ther- 
mometer, while the latter is made known through the 
organ of sight. Rays of radiant heat, always moving in 
straight lines when the medium through which it passes 
permits it, do not impart any heat to a surrounding 
medium by difltusion, and thus materially differs from con- 
duction of heat, in which the heat always travels from hot- 
ter to colder portions of an unequally heated medium. The 



RADIANT HEAT. 187 



entire process of radiation consists of three distinct parts — 
emission, absorption and transmission. 

Amission of radiant heat — Radiant heat is emitted in 
straight lines in all directions from a radiating point. 
Hence, the quantity of heat which, in a given time, falls on 
a given substance from a radiating point is inversely pro- 
portional to the square of the distance of that surface from 
the radiating point. 

It is a matter of universal experience that, under other- 
wise similar circumstances, a given body gives out more 
heat in a given time the hotter it is. Temperature, there- 
fore, is one condition which determines the emissive power 
of bodies for heat; but further examination shows that it 
is not the only condition upon which this phenomenon 
depends, as it is well known that different substances have 
very different powers of emitting heat, even when their 
temperatures are exactly the same. 

Absorption of radiant heat — When radiant heat arrives 
at the surface of a boiler, for example, part of it is always 
reflected, either regularily or diffusively ; but this reflec- 
tion is never complete. Another portion of the heat pene- 
trates into the iron, and, according to the particular prop- 
erties of the latter, is either wholly or in part transmitted 
through it, or is wholly or in part annihilated, causing an 
increase of temperature in the body. It is this extinction 
of radiant heat, in causing rise in temperature in material 
bodies, that constitutes the phenomenon of absorption. 



188 



A TREATISE ON STEAM BOILEKS. 



TABLE LV. 

COMPARATIVE RADIATING OR ABSORBENT AND REFLECTING POWERS OF 

SUBSTANCES. 



SUHSTANCK. 



Water 

Ice 

Cast iron, brightly polished 

Wrought iron, polished 

Zinc, polished 

Steel, polished 

Tin 

Brass, cast, bright polished. 
Copper, hammered or cast.. 





POWERS. 




RADIATING 

OR 
ABSORBING. 


REFLECT- 




ING. 


100 









85 






15 


25 






75 


23 






77 


19 






81 


17 






83 


15 






85 


t 
1 






93 
93 



The reflecting power of a body is the complement of 
its absorbing power. The latter varies with the nature of 
the source of heat, with the condition of the substance, 
and with the inclination of the direction of the heat radiated 
upon the body. The absorbing power of a metallic surface 
is much less than the reflecting power, and the latter 
increases as the surface is highly polished. 

Radiation of heat from combustibles — Few experiments 
have been made to determine the proportion which the 
radiant heat bears to the total heat in different combusti- 
bles. M. Peclet, by means of a simple apparatus, consist- 
ing of a cage suspending the combustibles within a hollow 
cylinder filled with water in an annular space, ascertained 
that the proportion of the total heat radiated from differ- 
ent combustibles was as follows : 



CONDUCTION OF HEAT. 189 

Total heat 100 

Radiant heat from wood 25 per cent, nearly. 

Radiant heat from charcoal 50 per cent, nearly. 

Radiant heat from oil 20 per cent, nearly. 

The transmission of radiant heat is controlled by the 
same laws as that of light, and has its origin in the oscil- 
latory motion of the ultimate particles of matter. Trans- 
mission consists, then, in the transference of this motion 
from a heated body called the emissive to another called 
the absorbing body. This transmission never occurs except 
when heat passes out of a hot body to enter a colder one. 

Conduction is the transfer of heat between two bodies 
or parts of a body which touch each other. It is distin- 
guished into internal and external conduction, according as 
it takes place between the parts of one continuous body, 
or through the surface of contact of a pair of distinct 
bodies. 

If one part of a body, such as a bar of iron, is at a 
higher temperature than the rest, and it be left to itself, it 
will in time acquire a uniform temperature throughout the 
mass of metal, the hot part losing heat, the cold part gain- 
ing heat. This tendency towards equalization of tempera- 
ture is what is known as internal conduction of heat. 

The rate at which conduction, whether internal or 
external, goes on, being proportional to the area of the 
section or surface through which it takes place, ma}^ be 
expressed in the form of so many thermal units per square 
foot of area loer hour. [Rankine]. 

The following table gives the comparative conducting 
power of different metals : 

Silver 10.0.0 

Copper 73.6 

Brass 23.6 

Tin 14.5 



190 A TREATISE ON STEAM BOILERS. 

Iron 119 

Steel 11.0 

Lead 8.5 

German Silver 6.3 

As a general rale it will be found that the densest 
bodies are the best conductors of heat. 

Conduction of heat by liquids — In consequence of the 
diminution of density which takes place almost univer- 
sally in liquids when they are heated, an increase of tem- 
perature is rapidly communicated by convection to the 
whole of a quantity of liquid when heat is applied to it 
from below. Hence, it was formerly supposed that liquids 
possessed a high degree of conductivity for heat. When 
heat is imparted to a liquid from above, so that the expan- 
sion of the heated portions can not cause them to rise, and 
so produce a circulation of the liquids, the communication 
of heat from one part of a liquid to another takes place 
with extreme slowness; and thus heat acts for a long time 
upon the upper part of a column of water and gradually 
penetrates downwards and follows the same law of con- 
duction as observed in metals, being only less in degree. 
From experiments it appears that the conductivity of. 
water is to that of copper as 9 to 1000. 

Convection ofheat^ means the transfej and diffusion of the 
state of heat in a fluid mass, by means of the motion of the 
particles of that mass. It is only by the continual circulation 
and mixture of the particles of the fluid, that uniformity 
of temperature can be maintained in the fluid mass, or 
heat transferred between the fluid mass and a solid body. 
In a steam boiler, it is favorable to economy of fuel that 
the motion of the water and steam should, on the whole, 
be opposite to that of the flame and hot gas from the 
furnace. 



HEATING SURFACE. 191 



Heating surface — One of the first tilings to be known, 
after the selection of a particular type of boiler, is the 
amount of heating surface it ought to have to evaporate a 
certain quantity of water. As the evaporation is depend- 
ent largely upon the construction of the boiler itself, 
together with its furnace, whether situated within itself or 
underneath it, there is an element of uncertainty as to 
quantity, introduced at a very early stage in any proposed 
calculations. 

Internal heating surface — The most effective heating sur- 
face in a boiler is a flat or concave plate or crown sheet, 
immediately over the fire. For several reasons, a concave 
plate, acting as a crown sheet, is to be preferred whenever 
practicable, on account of its being well adapted to receive 
the radiant heat from the fire, but more especially on 
account of its permitting a better circulation of water 
inside the boiler, because of the absence of crown bars and 
other fixtures necessary to the proper staying of a large, 
flat surface. 

In this case, the fire is made in a furnace, surrounded- 
on all sides, except the bottom, with water spaces. 

The relative values of heating surfaces in the different 
portions of a boiler can not be said to have been definitely 
settled. It is generally known, however, that in fire box 
boilers, for example, by far the greater portion of the evap- 
oration is carried on in the fire box end of the boiler. 

External heating surface — In horizontal tubular boilers 
the shell is far more efficient than the tubes. The efficiencg 
and the quantity of heating surface in a boiler should never 
be confounded, and in designing a boiler, the former of the 
two is always to be preferred over the latter. The gener- 
ally received notion that a boiler should present no heat 
absorbing surfaces to obstruct the flow of heated gases,. 



192 A TREATISE ON STEAM BOILERS, 

borders on an absurdity. After complete combustion has 
taken place in the furnace, and the heated products have 
begun their flow towards the chimney, then the more they 
are deflected and turned from a straight course and made 
to impinge against heat absorbing surfaces in the boiler, 
the more heat will the gases give up, and, in consequence, 
the more water will be evaporated per pound of coal. 
This will, of course, interfere greatly with a natural or 
chimney draught. A forced draught, however, may be 
used with much greater economy and compel a flow of 
gases. 

Position of heating surface — The relative values due to 
the different positions of heating surface have been deter- 
mined by direct experiments with the following approxi- 
mate results : 

One square foot of heating surface placed at right 
angles to the current of heated gases so as to receive them 
by direct impact, was found to equal four square feet when 
placed diagonally to the current, or eight square feet when 
placed in a direction parallel to their flow. This shows the 
importance of securing a direct impact of heated gases 
against the absorbing surfaces of the boiler, whenever the 
designs can favor it. In all ordinary boiler construction 
this matter is wholly overlooked or disregarded, more atten- 
tion having been paid to it in the designing of sectional 
boilers than, perhaps, any other class. 

Heating surface of tubes and flues — The value of the 
heating surface of horizontal and vertical tubes has been 
greatly overrated. In almost all calculations the surface 
of tubes is counted in with that of the shell as being of 
equal value. A greater mistake can be hardly made. The 
results of experiments made to determine the value of 
tube heating surface shows it to be about ^ that of fur- 



HEATING SURFACE OF TUBES. 193 

nace heating surface. Mr. C. Wye Williams had an experi- 
mental boiler made in order to determine the exact values 
of heating surface in tubes in relation to their length. 
This boiler had twenty -five tubes, six feet long and two 
and a half inches in diameter. 

The boiler was fitted with three water tight compart- 
ments ; the first partition was placed at a distance of one 
foot from the front end, and a similar partition one foot 
from the rear end; thus making the two end compart- 
ments one foot long each, and the middle one four feet 
long. After having made suitable connections with a fur- 
nace at what we shall call the front end, it w^as observed 
that the water was brought to the boiling point in the first 
compartment (which was one foot long), after an interval 
of twenty-three minutes from the time of starting the 
fires ; in the second or four feet compartment it required 
forty-eight minutes; and in the third or last compartment, 
fifty-nine minutes. The water having been brought to the 
boiling point, it was continued by careful and regular firing 
for three hours, with the following results : 

First compartment, one foot long, two hundred and 
forty pounds water evaporated. 

Second compartment, four feet long, an average evapo- 
ration of seventy pounds of water for each of the four feet 
in length. 

Tiiird compartment, one foot long, fifty pounds water 
evaporated. 

Showing that the first foot of tube heating surface 
is the one of greatest value, and that long tubes add but 
little to the steaming capacity of a boiler. 

In another experiment, it was shown that the first inch 
in length of tube was equal in efficiency to the next ten 
inches. 

However valuable Mr. Williams' experiments may be 
in showing the popular error in estimating the value of 
(14) 




194 A TREATISE ON STEAM BOILERS. 

tube heating surface, it must not be supposed that it is 
next to worthless. The record of the ordinary horizontal 
tubular boiler, so largely used in this country, shows that 
tube surface has value, but to what extent, as compared 
with the shell, is not certainly known. 

Figure 44 represents a cross section of a tube; from an 
inspection it will be seen that the most 
effective portion for heating is the top of 
the tube, which is represented by 1. As 
there is no perceptible amount of heat given 
off at the bottom of the tube, it is repre- 
sented by ; the sides of the tube are about 
half as effective as the top ; then, adding together, 

1 + i + + i _ 1 

or, the effective heating surface of a tube, is approximately 
only one-half its circumference multiplied into its length. 

The precise action of a column of heated gases in a flue 
is not known, but, from the fact that the gases escape at a 
temperature several times greater than the temperature of 
a compartment filled with water, as already described 
(page 193), we are led to infer that the central portion of 
the column of gases does not touch or give up any of its 
heat to the fine. This may be illustrated by the following 
diagram : * 



700 


600 


500 


400 


300 


700 
700 


700 
700 


700 
700 


700 
700 


700 
700 


700 


600 


500 


400 


300 



Figure 45, 
* Spon's Dictionary of Engineering 



EVAPORATION AND HEATING SURFACE. 195 

The several lines are supposed to represent the sections 
or strata of heated products passing through it, entering 
at a temperature of 700° and issuing at 540°. In this case 
the outer section, being next, and in contact with, the iron 
flue surface, will give out heat and be reduced, say to 300°, 
on arriving at the end of the flue. 

Evaporation as modified by kind and extent of heating sur- 
face — The heating surface of a boiler is often used as a 
measure of its evaporative capacity, and as engines are 
usually rated by the horse power, boilers have had imposed 
upon them a similar rating, so that the capacity or power 
of a steam boiler is oftener rated by the horse power than 
b}^ any other method, and this still further complicates 
matters, because the horse power of a boiler is usually 
made to correspond to that of the engine for which it is to 
furnish the steam, the power of which varies with the 
pressure of steam, and, as to whether it is a slide valve 
engine controlled by an ordinary governor, or an automatic 
cut off engine — the latter engine requiring a less quantity 
of water per horse power than the former. That the evap- 
orative power of the boiler depends upon the heating sur- 
face there can be no doubt, for it is by this means alone 
that the heat of combustion is transferred to the water. 
This transfer may be either direct, as in the case of such 
portions of the boiler as are situated immediately around 
or above the fire ; or, it may be indirect, as in the case of 
flues and tubes. The former is by direct radiation from 
the fire, the latter receives heat only by conduction. The 
relative values of the two kinds of .heating surface are, for 
equal surfaces and similar conditions, about ^yq to one in 
favor of direct heating. 

The material of which the boiler is made and its thick- 
ness will have an effect on its evaporative power; the 
former only when perfectly clean, the latter at all times. 



196 A TREATISE ON STEAM BOILERS. 

The quantities of heat transmitted through plates of 
metal, one inch thick, for one degree Fahrenheit difierence 
of temperature, per hour, as determined hj M. Peclet, are 
as follows : 

Copper ...' 555 units of heat. 

Iron 225 units of heat. 

Zinc 225 units of heat. 

Tin 177 units of heat. 

Lead : 112 units of heat. 

This, it should he ohserved, is for metals perfectly clean. 
M. Peclet found that all metals conduct heat about alike 
when their surfaces became dull. His experiments were 
with two boilers, one of which was made of copper and 
the other of cast iron. These were both exposed to an 
intense heat, and placed into the flame in such a manner 
that their surfaces became dulled; the evaporation was 
then carefully noted and. was found to be about twenty 
pounds of water per square foot of surface per hour. In 
some experiments by Mr. James R. Napier, Avith small 
boilers of similar materials, and placed over a gas flame, 
the quantities of water evaporated were practically the 
same. Other experiments on a larger scale show that after 
a few days use there is practically no difterence between 
the evaporation in an iron or in a copper boiler. This 
fact shows that the latter metal possesses no advantage 
over the former cheaper metal if allowed to get coated 
with soot. This practically confines the economical use 
of copper to the fire boxes of internally fired boilers, where, 
on account of the intense heat, it has no chance to become 
coated with soot. For the same reason there is no econ- 
omy in the use of copper tubes in tubular boilers, unless 
kept perfectly clean. 

In regard to thickness, it is known that the resistance 
to internal conduction is proportional to the distance the 
heat has to traverse, or, in other words, to the thickness 



TRANSFER OF HEAT. 197 



of the plate. The evaporative effeciency also depends, and 
inversely, on the difference of the temperatures between 
the two sides of the plate through which the heat is to 
pass. The number of heat units which will pass through 
a square foot of iron plate per hour may be found in the 
following manner : 

From the temperature of the gases in the furnace and in contact with the 
boiler, subtract the temperature of the water in the boiler ; divide this hy the 
thickness of the plate, multiplied by .0096, which will give the quantity sought for. 
M. Peclet gives the decimal .0096 as the co-efficient of thermal resist- 
ance found by experiment. If for copper plates, then .0040 may be 
used instead. 

In the preceding paragraph uo account was taken of 
the resistance to external conduction on the one side, nor 
the resistance to the emission on the other. In order to 
arrive at the exact amount of heat which actually passes 
from the heated gases through the plates and taken up by 
the water, the total thermal resistance, both external and 
internal, must be taken into account. 

In order to make any such calculation it will be neces- 
sary to know, 

1. The resistance to the absorption of heat by the 
face of the plate next the heated gases. 

2. The resistance to emission on the other side of the 
boiler plate which is in contact with the water. 

3. The numerical value of the co-efficient of thermal 
resistance of the boiler plate. 

4. The thickness of the boiler plate in inches. 

5. The temperature of the heated gases, and 

6. The temperature of the water in the boiler. 

The quantity of heat transmitted may be found in this 
way : 

Subtract the temperature of the water from that of 
the heated gases, and divide the remainder by a divisor 



198 



A TREATISE ON STEAM BOILERS. 



consisting of the co-efficient (3) multiplied by the thickness 
o the boiler plate, to which is to be added the resistance 
to absorption and the resistance to emission. This quo- 
tient will be the quantity of heat, in heat units, transmitted 
to the water. 

The extent of heating surface in ordinary land boilers 
is dependent upon the length and diameter of the shell, 
the number and size of the tubes or flues. 

In setting boilers in brick work it is customary to carry 
up the side walls parallel, and when a few inches below the 
water line of the boiler to set the bricks in by successive 
steps, as shown in figure 46. This portion of the circumfer- 
ence multiplied into the length 
will give the heating surface 
of the shell. The next table 
gives the distance in feet for 
portions of circumferences, and 
all that is necessary to do in 
order to determine the heating 
surface of any shell is to know 
what portion of the circumfer- 
ence is used; find the number 
in the table where such fraction 
of circumference and diameter 
of the boiler intersect, and multiply the figures so found 
by the length of the boiler in feet. This will give the 
heating surface of the shell in square feet. 




Figure 46. 



HEATING SURFACE. 



199 



TABLE LVL 

TABLE OF PARTIAL CIRCUMFERENCES OF BOILER SHELLS, FROM TWENTY- 
FOUR TO SEVENTY-TWO INCHES IN DIAMETER. 



DIAMETER OF 




PORTIONS 


OF CIRCUMFERENCE. 




BOILEK. 


WHOLE. 


3 

4 


f 


1 


i 


INCHES, 


FEET. 


FEET. 


FEET. 


FEET. 


FEET. 


24 


6.28 


4.71 


4.19 


3.93 


3.14 


26 


6.81 


5.11 


4.54 


4.25 


3.40 


28 


7.33 


5.50 


4,89 


4.58 


3.67 


30 


7.85 


5.89 


5.24 


4.91 


3.93 


32 


8.38 


6.28 


5.59 


5.24 


4.19 


34 


8.90. 


6.68 


5.93 


5.56 


4.45 


36 


9.42 


7.07 


6.28 


5.89 


4.71 


38 


9.95 


7.46 


6.63 


. 6.22 


4.97 


40 


10.47 


7.85 


6.98 


6.55 


5.24 


42 


11.00 


8.25 


7.33 


6.87 


5.50 


44 


11.52 


8.64 


7.68 


7.20 


5.76 


46 


12.04 


9.03 


8.03 


7.53 


6.02 


48 


1257 


9.42 


8.38 


7.85 


6.28 


50 


13.09 


9.82 


8.73 


8.18 


6.55 


52 


13.61 


10.21 


9.08 


8.51 


6.81 


54 


14.14 


10.60 


9.42 


8.84 


7.07 


56 


14.66 


11.00 


9.77 


9.16 


7.33 


58 


15.18 


11.39 


10.12 


9.49 


7.59 


60 


15.71 


11.78 


10.47 


9.82 


7.85 


62 


16.23 


12.17 


10.82 


10.14 


8.12 


64 


16.76 


12 57 


11.17 


10.47 


8.38 


66 


17.28 


12.96 


1 1 f,2 


10.80 


8.64 


68 


17.80 


13.35 


11.87 


11.13 


8.90 


70 


18.33 


13.74 


12.22 


11.45 


9.16 


72 


18.85 


14.14 


12.57 


11.78 


9.43 



200 



A TREATISE ON STEAM BOILEKS. 



In table LYII may be found the external beating surface 
in square feet for one lap welded wrought iron tube. The 
lengths given in the table will meet every ordinary require- 
ment. If, however, the boiler requires tubes of a differ- 
ent length from those in the table, the heating surface given 
in the second column, multiplied into the length of such a 
tube, will give its area of heating surface in square feet. 



TABLE LVII. 

SHOWING THE EXTERNAL HEATING SURFACE IN ONE LAP WELDED 
BOILER TUBE OF THE FOLLOWING DIMENSIONS: 



DIAM- 
ETER 






LENGTH IN FEET. 






IN 
INCHES. 


1 


6 


8 


10 


12 


14 


16 


1 


.262 


1.57 


2.09 


2.62 


3 14 


3.66 


4.19 


n 


.327 


1.96 


2.62 


3.27 


3.92 


4.58 


5.24 


n 


.393 


2.36 


3.14 


3.93 


4.75 


5.50 


6.28 


If 


.458 


2.75 


3.66 


4.58 


5.50 


6.41 


7.33 


2 


.524 


3.14 


4 19 


5.24 


6.29 


7.33 


8.38 


2i 


.589 


3.53 


4.71 


5.89 


7.07 


8.25 


9.42, 


2^ 


.655 


3.93 


5.24 


6.55 


7.86 


9.17 


10.47 


2f 


.720 


4.32 


5.76 


7.20 


8.64 


10.08 


11.52 


3 


.785 


4.71 


6.28 


7.85 


9.42 


10.99 


12.57 


H 


.850 


5.10 


6.80 


8.50 


10.20 


11.90 


13.61 


3J 


.916 


5.50 


7.33 


9.16 


10.99 


12.82 


14.66 


3f 


.982 


5.89 


7.86 


9.82 


11.78 


13.75 


15.71 


4 


1.047 


6.28 


8.38 


10.47 


12.56 


14.66 


16.76 


4^ 


1.178 


7.07 


9.42 


11.78 


14.14 


16.49 


'18.85 


5 


1.309 


7.85 


10.47 


13.09 


15.71 


18.33 


20.94 


6 


1.570 


9.42 


12.56 


15.70 


18.84 


21.98 


25;i3 



The next table (LVIII) shows the external heating 
surface in one flue, from six to twenty-four inches diameter. 
In case the length in feet given in the table does not corre- 



HEATING SURFACE. 



201 



spond to the length of the boiler, any column containing 
a fractional length may be used as a convenient multiplier, 
or the figures in two columns may be added together, thus: 
Required the heating surface in one flue, seventeen inches 
diameter, twenty-six feet long ? This length is not con- 
tained in the table, but by adding together the figures in 

53.41 

columns twelve and fourteen feet, thus, y^fi- the correct 
amount is given. 

TABLE LVIII. 

SHOWING THE EXTERNAL HEATING SURFACE IN ONE FLUE OF THE 

FOLLOWING DIMENSIONS. 



DIAM- 
ETER 


LENGTH IN FEET. 


INCHES. 


1 


12 


14 


16 


IS 


20 


22 


6 


1.5708 


18.85 


21.99 


25.13 


28.27 


31.42 


34.56 


7 


1.8326 


21.99 


25.66 


29.32 


32.99 


36.65 


40.32 


8 


2.0944 


25.13 


29.32 


33.51 


37.70 


41.89 


46.08 


9 


2.3562 


28.27 


32.99 


37.70 


42.41 


47.12 


51.84 


10 


2.6180 


31.42 


36.65 


41.89 


47.12 


52.36 


57.60 


11 


2.8798 


34.56 


40.32 


46.08 


51.84 


57.60 


63.36 


12 


3.1416 


37.70 


43.98 


50.27 


56.55 


62.83 


69.12 


13 


3.4034 


40.84 


47.65 


54.45 


61.26 


68.07 


74.87 


14 


3.6652 


43.98 


51.31 


58.64 


65.97 


73.30 


80.63 


15 


3.9270 


47.12 


54.98 


62.83 


70.69 


78.54 


86.39' 


16 


4.1888 


50.27 


58.64 


67.02 


75.40 


83.78 


92.15 


17 


4.4506 


53.41 


62.31 


71.21 


80. J 1 


89.01 


97.91 


18 


4.7124 


,56.55 


65.97 


75.40 


84.82 


94.25 


103.67 


19 


4.9742 


59 69 


69.64 


79.59 


89.54 


99.48 


. 109.43 


20 


5.2360 


62.83 


73.30 


83.78 


94.25 


104.72 


115.1» 


21 


5.4978 


65.97 


76.97 


87.96 


98.96 


109.96 


120.95 


22 


5.7696 


69.24 


80.77 


92.31 


103.85 


115.39 


126.93 


23 


6.0214 


72.26 


84.30 


96.34 


108.39 


120.43 


132.47 


24 


6.2832 


75.40 


87.96 


100.53 


113.10 


125.66 


138.23 



202 A TREATISE ON STEAM BOILERS. 

Grate area — From results of experiments made person- 
ally, and from an inspection of experiments made by 
others, the writer has about come to the conclusion that 
there is no such thing as a fixed relation between grate area 
and heating surface, suited even to average conditions. 

Among the things to be taken into account, in fixing 
the grate area, are, 

The quantity of water to be evaporated. 

The kind and quality of fuel to be used. 

The details of the boiler and setting. 

"Whether a natural or forced draft is to be employed. 

Whether the water used will form scale. 

The ability and faithfulness of the fireman. 

The theoretical grate area may be fixed when the first 
three of the above conditions are known ; subject, how- 
ever, to the modifying influences of the other three. 

There are several empirical rules for fixing the grate 
area, among which may be mentioned that of Armstrong, 
whose rule it was, to allow a square foot of grate area for 
each cubic foot of water to be evaporated per hour, and 
one square yard of heating surface per horse power, for 
ordinary coal. The grate area might be lessened to three- 
fourths of a square foot for good coal, and to half a square 
foot for the best coal. 

Another rule is, to divide the number of pounds of 
water to be evaporated per hour, from and at 212° Fahren- 
heit, by the following numbers, which will give the area in 
square feet : 

If for cylinder boilers, by 75 

For flue boilers, by 77 

For horizontal tubular boilers, by 78 

For vertical tubular boilers, by 79 

For locomotive and portable boilers 80 

The amount of coal burned per hour, per square foot of 
grate surface, is, for stationary boilers with natural draft, 



GRATE SURFACE. 203 



Bituminous coal 10 to 25 pounds. 

Semi anthracite 10 to 20 pounds. 

Hard anthracite 8 to 16 pounds. 

When a forced draft is used, these figures may be 
doubled, if necessary, in which case thicker fires should be 
used, and will require greater care in firing, that the heat 
may not be wasted by the strong draft. 

The rate of combustion per hour per square foot of 
grate being known, the area of grate surface may be 
approximately fixed as follows : 

For externallj' fired boilers, with moderate draft, .08 sqr. ft. per lb. of coal. 

For externally fired boilers, with quick draft 06 sqr. ft. per lb. of coal. 

For externally fired boilers, with forced draft 04 sqr. ft. per lb. of coal. 

For internally fired boilers, with quick draft 03 sqr. ft. per lb. of coal. 

For internally fired boilers, with forced draft 02 sqr. ft. per lb. of coal. 

For locomotive boilers 01 sqr. ft. per lb. of coal. 

These numbers are nearly the reciprocals of the num- 
ber of pounds of coal burned per hour per square foot of 
grate. 

A common method of fixing the area of grate surface 
is to build the furnace walls from four to four and a half 
inches distant from the side of the boiler, the length 
of the grate varying from forty-two inches to six feet. 
Table LXYIII gives the sizes used by the writer in 
ordinary boiler settings; the area is larger than is neces- 
sary for good coal and for a quick draft. The best way to 
reduce it is to lay a course of brick Avork along each side 
wall until the area is such that the most economical rate of 
combustion is secured. In this way the area of grate miay 
be suited to the local conditions which aflect any particular 
case, but will furnish no reliable data for another section 
of the country, or one in which the fuel, draft and atten- 
tion to firing may be different. 

Evaporation — In order to evaporate a given quantity of 
water in a given time two things are to be taken into 



204 



A TREATISE ON STEAM BOILEES. 



account — first, the area of heating surface, and, second, the 
average rate of transmission of heat per square foot of 
surface. Evaporation is commonly reckoned by the num- 
ber of pounds of water which one pound of net combusti- 
ble will convert into steam at atmospheric pressure, the 
feed water being supplied and evaporated at 212° Fahr. 
Other things being equal, it would be expected that the 
boiler which presents the greater amount of heating sur- 
face would evaporate the greatest quantity of water; prac- 
tically, the rate of evaporation varies considerably for dif- 
ferent parts of the sarne boiler, the portion nearest the fire 
evaporating the most water in any given time. The clean- 
liness of the boiler, both external and internal, has much 
to do with the evaporation. If a coating of soot accumu- 
lates along the lower side of the boiler, or in the flues, it 
will interfere with the transfer of heat, because soot is a 
bad conductor. If a coating of scale accumulates inside 
of the boiler it will also interfere with the rapid transmis- 
sion of heat, for the reason that scale, like soot, is a bad 
conductor, and coming in between the iron and the water 
prevents the latter from receiving the heat transmitted 
through the boiler plates. ETeither of these can be taken 
into account in determining the theoretical evaporating 
capacity of a boiler, because of the constantly varying 
quantities of these two non-conductors. 

It has been demonstrated, experimentally, that one 
pound of good coal will evaporate, under favorable condi- 
tions, from nine to twelve pounds of water from and at 
212° Fahrenheit. The rate of evaporation, per square foot 
of heating surface, will vary from 1.5 to 9 pounds. The 
actual rate of evaporation, per square foot of heating sur- 
face, for the diflerent kinds of boilers, varies within such 
wide limits as to practically render worthless the formulas 
bearing on this subject. 



PROPERTIES OF STEAM. 



205 



The following tables (LIX and LX) may be of use, 
however, in approximating equivalent evaporation for dif- 
ferent temperatures of feed water between 32° and 212° 
Fahrenheit: 

TABLE LIX. 

PROPERTIES OF SATURATED STEAM. 



PRESSURE. 


TEMPERA- 
TURE IN 
FAHREN- 


VOLUME. 


LATENT 
HEAT IN 
FAHREN- 


TOTAL HEAT 

REQUIRED TO 

GENERATE ONE 


BY 

STEAM 
GAUGE, 




COM- 


CUBIC 
FEET OF 


POUND OF STEAM 

FROM WATER 

AT 32° 


TOTAL. 


HEIT 
DEGREES. 


PARED 

WITH 

WATER. 


STEAM 

FROM ONE 

POUND OF 

WATER. 


HEIT 
DEGREES. 


FAHRENHEIT, 

UNDER CONSTANT 

PRESSURE, 

IN HEAT UNITS. 





15 


212.0 


1642 


26.36 


965.2 


1146,1 


5 


20 


228.0 


1229 


19.72 


952.8 


1150.9 


10 


25 


240.1 


996 


15.99 


945.3 


1154.6 


15 


30 


250.4 


838 


13.46 


937.9 


1157.8 


20 


35 


259.3 


726 


11.65 


931.6 


1160.5 


25 


40 


267.3 


640 


10.27 


926.0 


1162,9 


30 


45 


274.4 


572 


9.18 


920.9 


1165,1 


35 


50 


281.0 


518 


8.31 


916.3 


1167.1 


40 


55 


287.1 


474 


7.61 


• 912.0 


1169.0 


45 


60 


292.7 


437 


7.01 


908.0 


1170.7 


50 


65 


298.0 


• 405 


6.49 


904.2 


1172,3 


55 


70 


302.9 


378 


6.07 


900 8 


1173.8 


60 


75 


307.5 ' 


35^ 


5.68 


897.5 


1175.2 


65 


80 


312.0 


333 


5.35 


894.3 


1176,5 


70 


85 


316.1 


314 


5.05 


891.4 


1177.9 


75 


90 


320.2 


298 


4.79 


888.5 


1179,1 


80 


95 


324.1 


283 


4.55 


885.8 


1180.3 


85 


100 


327.9 


270 


4.33 


883.1 


1181.4 


90 


.105 


331.3 


257 


4.14 


880.7 


1182.4 


95 


110 


334.6 


247 


3.97- 


878.3 


1183.5 


100 


115 


338.0 


237 


3.80 


875.9 


1184.5 



206 



A TREATISE ON STEAM BOILERS. 



TABLE LIX— Continued. 



PRESSURE. 


TEMPERA- 
TURE IN 
FAHREN- 
HEIT 
DEGREES. 


VOLUME. 


LATENT 
HEAT IN 
FAHREN- 
HEIT 
DEGREES. 


TOTAL HEAT 

REQUIRED TO 

GENERATE ONE 


BY 

STEAM 
GAUGE. 


TOTAL. 


COM- 
PARED 

WITH 
WATER. 


CUBIC 
FEET OF 

STEAM 

FROM ONE 

POUND OF 

WATER. 


POUND OP STEAM 
FROM WATER 

AT 32° 

FAHRENHEIT, 

UNDER CONSTANT 

PRESSURE. 

IN HEAT UNITS.. 


105 


120 


341.1 


227 


3.65 


873.7 


1185.4 


110 


125 


344.2 


219 


3.51 


871.5 


1186.4 


115 


130 


347.2 


211 


3.38 


869.4 


1187 3 


120 


135 


350.1 


203 


2.27 


867.4 


1188.2 


125 


140 


352.9 


197 


3.16 


865.4 


1189.0 


130 


145 


355.6 


190 


3.06 


863.5 


1189.9 


135 


150 


358.3 


184 


2.96 


861.5 


1190.7 


140 


155 


361.0 


179 


2.87 


859.7 


1191.5 


145 


160 


363 4 


174 


2.79 


857.9 


11922 


150 


165 


366.0 


169 


2.71 


856.2 


1192.9 


155 


170 


368.2 


164 


2.63 


854.5 


1193.7 


160 


175 


370.8 


159 


2.56 


852.9 


1194.4 


165 


180 


372.9 


155 


2 49 


851.3 


1195 1 


170 


185 


375.3 


151 


2.43 


849.6 


1195.8 


175 


190 


377.5 


148 


2.37 


848.0 


1196.5 


180 


195 


379.7 


144 


2.31 


846.5 


1197.2 



The above table gives the values of all the properties 
of saturated steam usually required in any calculations 
connected with steam boilers ; and by the aid of the next 
table, taken from Professor Rankine's Treatise on the 
Steam Engine, the equivalent evaporation from and ' at 
212° may be easily determined, the actual number of pounds 
of water evaporated per pound of coal and the temperature 
of the feed water being known. 



FACTORS OF EVAPORATION. 



207 



TABLE LX. 

FACTORS OF EVAPORATION. 



TEMPERATURE 


TEMPERATURE OF THE FEED WATER. 


OP THE STEAM. 


.32° 


50° 


68° 


86° 


104° 


122° 


140° 


158° 


176° 


194° 


212° 


212° 


1.19 


1.17 


1.15 


1.13 


1.11 


1.10 


1.08 


1.06 


1.04 


1.02 


1.00 


230° 


1.20 


1.18 


1.16 


1.14 


1.12 


1.10 


1.08 


1.06 


1.04 


1.02 


1.01 


248° 


1.20 


1.18 


1.16 


1.14 


1.13 


1.11 


1.09 


1.07 


1.05 


1.03 


1.01 


266° 


1.21 


1.19 


1.17 


1.15 


1.13 


1.11 


1.09 


1.07 


1.06 


1.04 


1.02 


284° 


1.21 


1.20 


1.18 


1.16 


1.14 


1.12 


1.10 


1.08 


1.06 


1.04 


1.02 


302° 


1.22 


1.20 


1.18 


1.16 


1.14 


1.12 


1.11 


1.09 


1.07 


1.05 


1.03 


320° 


1.22 


1.21 


1.19 


1.17 


1.15 


1.13 


1.11 


1.09 


1.07 


1.05 


1.03 


338° 


1.23 


1.21 


1.19 


1.17 


1.15 


1.14 


1.12 


1.10 


1.08 


1.06 


1.04 


356° 


1.23 


1.22 


1.20 


1.18 


1.16 


1.14 


1.12 


1.10 


1.08 


1.06 


1.04 


374° 


1.24 


1.22 


1.20 


1.18 


1.17 


1.15 


1.13 


1.11 


1.09 


1.07 


1.05 


392° 


1.24 


1.23 


1.21 


1.19 


1.17 


1.15 


1.13 


1.11 


1.09 


1.07 


1.06 


410° 


1.25 


1.23 


1.22 


1.20 


1.18 


1.16 


1.14 


1.12 


1.10 


1.08 


1.06 



The use of the above table will be illustrated in the 
solution of .the following example : 

A boiler evaporates nine pounds of water per pound of 
coal, the feed water being 68° and the pressure of steam 
one hundred pounds per square inch ; what is the equiv- 
alent evaporation from and at 212° ? 

The temperature of steam corresponding to one hun- 
dred pounds pressure, as seen from table LIX, is 338°. 
The factor of evaporation corresponding to this temper- 
ature, the feed entering the boiler at 68°, according to 
table LX is 1.19, which, multiplied by the pounds of water 
evaporated, will be 1.19 X 9 = 10.71 pounds of water per 
pound of coal. 

If any particular type of boiler had a regular rate of 
evaporation per square foot of heating surface, a series of 
tables might easily be calculated by which the probable 



208 



A TREATISE ON STEAM BOILERS. 



performance of a boiler might be given in advance of its 
manufacture, or if the rate of the transmission of the heat 
through the plates to the water was anything like constant, 
it might prove a useful factor in boiler calculations, but, 
unfortunately, neither of these have any practical value 
except for the first few days the boiler is used after com- 
pletion. 

The following table and rule from Northcott's Theory 
and Action of the Steam Engine shows the approximate 
mean rates of transmission of heat per square foot of heat- 
ing surface per hour, corresponding with various degrees 
of efficiency, and for the principal classes of boilers used 
in practice : 

TABLE LXI. 

SHOWING MEAN RATE OF TRANSMISSION OF HEAT THROUGH BOILER 

PLATES. 





INTERNALLY FIRED BOILERS OF THE 








CORNISH AND LANCASHIRE TYPES. 




LOCOMOTIVE 






coon TUBULAR 


BOTTiERS 


EFFICIENCY. 


SLOW COMBUS- 
TION AND 
SLUGGISH 
GAS AND WATER 
CIRCULATION. 


WITH GOOD 

CHIMNEY DRAFT 

AND 

CIRCULATING 

TUBES IN FLUES. 


BOILERS 
WITH BRISK 
COMBUSTION. 


WITH STRONG 
STEAM BLAST 

AND RAPID 
COMBUSTION. 




2,200° FAHR. 


2,600° FAHR. 


3,000° FAHR. 


3,500° FAHR. 


.50 


12,000 


15,000 


20,000 


30,000 


.55 


9,000 


12,000 


16,000 


23,000 


.60 


6,000 


9,000 


12,000 


17,000 


.65 


4,500 


7,000 


9,500 


13,500 


.70 


3,000 


5,000 


7,000 


.10,000 


.75 


2,300 


4,000 


5,500 


8,000 


.80 


1,500 


3,000 


4,000 


6,000 


.85 






3,300 
2,500 


4,800 
3,500 


.90 















HORSE POWER OF BOILERS. 209 

If we wish to know in advance what area of heating 
SLirface would be required in a tubular boiler to carry 100 
pounds of steam, and evaporate 60 cubic feet of water 
per hour, we first reduce the cubic feet of water to pounds, 
thus : 62.5X60:=3,750 pounds of water to be converted into 
steam. By referring to table LIX, we find the total heat 
required to generate one pound of steam from water at 32° 
Fahrenheit, in heat units, to be 1184.5; then, 1184.5X3750 
=4,441,875. If the efficiency of the furnace be .70 we 
find 7,000 in table LXI to be the mean rate of transmission ; 
then - Vq^oV "'^' =^ 6^^ square feet of heating surface required. 
This would require a tubular boiler, say 48 inches diameter 
X14 feet long, with 50 three-inch tubes. 

Rule — To ascertain the area of heating surface of a 
proposed steam generator, multiply the quantity of water 
to be evaporated in pounds by the heat expended per 
pound of steam. This quantity divided by the mean rate 
of transmission, as given in table LXI, for the required 
degree of efficiency, gives the area of heating surface in 
square feet. 

Horse power of boilers — Perhaps no more unsatisfactory 
unit has ever been employed than that of horse power as 
a unit of measurement for steam boilers ; and so long as it 
is applied to engines it will be, in all probability, applied 
to boilers. This term is in such general use among build- 
ers and users, alike, that it would be extremely difficult to 
substitute another rating to take its place. It has been 
proposed to rate boilers by their extent of heating surface. 
There is no particular objection to this, if heating surface 
was a thing of specific value. Boilers not only vary among 
themselves in the value of heating surface, but it is not of 
equal value in the same boiler. It has also been proposed 
to rate boilers by the amount of water evaporated into dry 
(15) 



210 A TREATISE ON STEAM BOILERS. 

steam per hour. This is not altogether satisfactory, for 
evaporation is dependent upon other things than the boiler 
itself: for example the construction of the furnace or 
boiler setting will have a marked influence on the rate of 
evaporation. The volume and force of the draft, together 
with the arrangement and size of the grate furnace, will 
also have much to do with the evaporation. The condi- 
tions of the heat absorbing surfaces, whether covered with 
scale on the inside or soot on the outside, will affect the 
rate of evaporation in a marked degree. The kind and 
quality of fuel used, the pressure of steam, and the tem- 
perature of the feed water are all hindrances. 

Boilers are usually made to furnish steam for an engine. 
It is the horse power of the engine which fixes the size of 
the boiler. If it is a high grade, automatic cut off engine, 
the quantity of water required will vary from one-third to 
one-half a cubic foot of water per hour per horse power. 
IP an ordinary slide valve engine, one cubic foot of water 
per hour per horse power; and there are direct acting 
pumping engines which require as much as two cubic feet 
of water per hour per horse power. 

I^eglecting the latter, which of the others is to be taken 
as the standard of evaporation? 

All things considered, perhaps the best practice is to 
allow one cubic foot of water per hour per horse power. 
This will be ample for ordinary slide valve engines, and 
will furnish a surplus of power often needed in the case 
of cut off engines. 

How much heating surface shall be allowed for this 
evaporation for different kinds of boilers? 

There is a rule of thumb, which has, long been in use 
and is still used (within very slight variations) in almost 
every boiler shop in the country, and is as follows : 



HORSE POWER OF BOILERS. 211 



SQUARE FEET OF HEATING SURFACE PER HORSE POWER: 

Cylinder boilers 9 

Flue boilers 12 

Tubular boilers 15 

Watts' rule for the horse power of boilers — One square foot 
of grate surface, one square yard ^f heating surface, one- 
half a square yard of water surface, represent one horse 
power; and these dimensions will suffice to evaporate one 
cubic foot of water per hour. 

The ,one square yard of heating surface has no refer- 
ence to the ordinary flue or tabular boilers as now con- 
structed. It was intended for the Waggon boiler, now 
obsolete. 

Another rule for tubular boilers is, 

Multiply the number of square yards of heating surface 
by the area of grate surface in square feet, and extract the 
square root, multiply this by 1.8 = H. P. of the boiler. 

Another rule for internally fired boilers of the Cornish 
and Lancashire types is, 

Multiply together the square yards of heating surface 
in the boiler, and the grate area in square feet, and extract 
the square root = H. P. of boiler. 

Another rule for cylinder boilers is, 
Divide the sectional area of the boiler by 6 = H. P. of 
boiler. 

Another rule for steam boilers, where the rate of evap- 
oration is assumed, and thus fixing the area of grate sur- 
face in square feet for any given boiler, the heating surface 
in square feet may be found as follows : 

Grate surface x 11 = heating surface for cylinder boilers. 
Grate surface x 17 ^ heating surface for flue boilers. 
Grate surface x 24 = heating surface for vertical tubular boilers. 
Grate surface x 26 = heating surface for portable boilers. 
Grate surface x 30 = heating surface for locomotive boilers. 



212 A TREATISE ON STEAM BOILERS. 

Professor 11. II. Thurston estimates that for the best 
steaDi engines (those using high pressures and working 
expansively), the quantity of water required to be evapo- 
rated per hour, per horse power, is equal to the constant 
150, divided by the square root of the pressure. The horse 
power is to be understood as that furnished by the indi- 
cator. The quantity of water required for the best Corliss 
engines, for example, using steam at one hundred pounds 
pressure, would be ascertained by this formula, as follows : 
Square root of 100 =: 10 ; then, ^^ = 15 pounds of water 
required per hour, per indicated horse power, or* about :| 
of one cubic foot. This, it should be understood, takes no 
account whatever of the losses incident to the generation 
of steam, but shows what the demand of the engine is 
upon the boiler. For good engines he increases the con- 
stant to 200. This would give for the same pressure twenty 
pounds of water, which accords closely with good average 
practice for high grade engines. 

By carrying this still further a constant of 350 might 
be employed for slide valve engines. This class of engines 
use steam of lower initial pressure, and with less economy 
than those above referred to. The usual point of cutting 
off is two-thirds stroke, which allows but one-third for 
expansion. If an initial pressure on the piston be assumed 
to be fifty pounds, or to get rid of a fraction we will say 
forty-nine pounds, we have : Square i^oot of 49 = 7; then, 
3A0. -— 50 pounds of water required per hour, per horse 
power, or nearly five-sixths of a cubic foot. 

Circulation — The power of a boiler is more dependent 
upon a proper circulation of the water in it than is gener- 
ally believed, or more attention would be paid to it in 
boiler design. When heat is applied to the shell of a boiler 
a movernent takes place in the water, and there is a motion 
of the particles, in which the heated ones below change 



CIRCULATION OF WATER. 



213 



places with the cooler particles above. This always takes 
place in any vessel when heated from below, and is the 
particular movement known as convection. The move- 
ment of these particles of the water upward not being the 
same throughout the boiler, causes a movement of the 
whole body of the water by producing upward currents 
in one portion and downward currents in another; it is 
this movement of the water which is to be understood as 
circulation, and not the movement of the heated particles 
changing places among themselves in the water. It is by 
these two combined movements, convection and circula- 
tion, that heat is diffused throughout the whole body of 
water and its temperature raised to a point where ebullition 
begins, accompanied by evaporation. 
Water is not a good conductor of 
heat; in fact, it is a very bad one. A 
familiar laboratory experiment to prove , 
this is take a long glass tube closed at 
the lower end, fill it with water, incline 
it at a suitable angle, and place a spirit 
lamp under the upper end; in this way 
the water in the upper portion of the 
tube maybe made to boil, while the water at the lower end 
will have scarcely risen in temperature. But if the heat 
be applied to the bottom of the tube, the contents will soon 
become heated, the bottom particles first; 
these expand because of their increased 
temperature, and being somewhat lighter 
than the other particles, are forced upwards 
through the superior density of the colder 
water above. This process of convection 
is continually increased until rapid circula- 
tion is established, which will continue so long as the con- 
ditions favorable to it remain. 




Figure 47. 




Figure 48. 



214 



A TREATISE ON STEAM BOILERS. 




Cylinder boilers are most favorable to circulation be- 
cause of the entire absence of tubes or flues, which always 
tend to impede it. If the temperature were uniform 
throughout the whole length of the boiler, the ebullition 

would also be going on the whole- 
length, but as the boiler is heated at 

one end the difference in temperature 

^^^^^^^^^^j, between the two ends may vary from 
^^^^B^^^^^BI 3?000° at the furnace to 800° at the end 
"-"i-*^^®^?«i;®r«atl/ where the gases pass into the chimney; 
^i®l®i^^p^ consequently the water at the furnace 
Figure 49 ^^^ ^^ ^^^ boiler will be more highly 

heated than at the other end. It is 
to be expected, and actually occurs, that the ebullition is 
more violent at this portion than any other in the boiler. 
It has the effect to raise the water level somewhat, and 
thus causes a surface flow from the front to the back end 
of boiler, thence downward to the bottom and along the 
shell to the furnace. This longitudinal circulation is favor- 
able to rapid evaporation. 

A verv common form of boiler is shown in fio^ure 47. 
When heat is applied directly underneath, 
the flow of water will be upward between 
the flues and down the sides. If more heat //®@©© ooo@' 
be applied to the sides than underneath, l\«o©© 11 SS/ 

the current of water is changed, and the \J*^ •••. 

downward flow is through the center and 
between the flues. Circulation is most dif- figure so. 
ficult in tubular boilers when the tubes are arranged zig- 
zag, as shown in figure 49. The upward circulation is 
interfered with by the water alternately impinging against 
the tubes, and thus changing its course between each hori- 
zontal row. A better arrangement is shown in figure 48, 
in which the tubes are placed in vertical rows, and still 
better, when the middle row of tubes are taken out, as 




CIRCULATrON OP WATER. 



215 




shown in figure 50. The circulation is then analogous to 
that described for flue boilers. The following abstract 
from a paper on the Circulation of Water in Steam Boil- 
ers,* is from the pen of Mr. Robert Wilson: 

" When, for the purpose of increasing the extent and 
efficiency of the heating surface, 
the large body of water is divided 
into smaller sections, connected 
by water passages, another move- 
ment of the body of water is usu- 
ally set up. In a Galloway boiler, 
for instance (see figure 51), there 
is, besides the ebullition, a move- 
ment of the water in some of the 
tapered tubes, which is due to the difference in the weight 
of two columns of water of the same height, but of differ- 
ent density, the lighter column being inside the tube and 
the heavier outside. In the tubes just behind the bridge, 
which are exposed to the highest temperature, the water is 
more highly heated and more dilated than that in the water 
spaces at the sides of the boiler. The unbalanced weight 
of the latter causes the water in the tubes to rise, and so a 
movement is set up, which becomes a continuous circula- 
tion so long as the necessary conditions exist. This upward 
motion of the whole body of water in the tube we may call 
draught circulation, which goes on at the same time as 
and independently of the ebullition. It is this draught 
ci^'culation that carries away the solid matters which are 
precipitated by the ebullition. Where there is simply ebul- 
lition, the heating surfaces become coated with incrusta- 
tion, where the nature of the feed water is such as to favor 
its formation. In G-alloway boilers this is shown by the 
thickness of the incrustation in the tubes, increasing with 
the dimunition of the draught circulation as we recede 
from the furnace. 

* From Engineering. 



216 A TREATISE OX STEAM BOILERS. 

'' The great accumulation of incrustration at the back 
end of these boilers is also in some measure due to the 
"tidal" circulation depositing the solid, matters here which 
have been precipitated nearer the furnaces. When the 
"draught" circulation in the Galloway tube near the fur- 
nace is arrested by, for instance, a Hopkinson safety valve 
float swaying a few inches above the mouth of the tubes, 
incrustation rapidly forms, in spite of the ebullition that 
goes on, and which is usually but wrongly credited with 
the merit of preventing scale from accumulating. 

"The shape of the tapered tube, with its greatest diam- 
eter at the top, whilst it favors the ebullition and the free 
escape of the steam particles as they are formed on the sides 
of the tube, at the same time reduces the rapidity of the 
draught circulation as the square of the increase of diam- 
eter. ^NTow, as the carrying away of the solid matter, 
which is deposited by the evaporation of the 'water, is 
mainly dependent upon the efficiency of the draught cir- 
culation, it follows that by reducing the draught efficiency 
the taper of the tube favors the formation and accumula- 
tion of incrustation, which impairs the efficiency of the 
heating surface of the tube. It would, therefore, appear 
that in some cases the tapering may actually tend to defeat 
the purpose for which the tube is introduced. It has 
liitherto been considered that a vertical taper tube is theo- 
retically better calculated to promote the generation of 
steam than a vertical straight tube. Bnt as the theory on 
which this conchision is based does not take account of all 
the processes involved, its correctness is nmore than ques- 
tionable. Of course, the practical constructive advantages 
and facility for cleaning afforded by the taper shape must 
be taken into consideration, as w^ell as the amount of taper 
in proportion to the length of the tube, the position of the 
tube in the boiler, and the nature of the feed w^ater, in 



CIRCULATION OF WATER. . 217 

determining whether a taper tube is better than a straight 
one in any given case. 

"In some cases we might, with advantages, even reverse 
the taper in order to promote the draught circulation, upon 
which is dependent, in some measure, the warming of the 
large body of dead water in boilers without external flues 
and having the fire grate above the shell bottom. The 
warming of this dead water is also slowly effected by the 
tidal circulation and b}' the diffusion downwards of the 
heat from the furnace, which takes place when the heat is 
imparted to the body of water more rapidly than it can be 
carried away by the convection upwards, which first takes 
place. 

"When there are many vertical tubes, as in a Galloway 
boiler, it will depend upon the relative areas of the side 
water spaces and of the tubes, the temperature of the gases 
in contact with the vertical and horizontal tubes at any 
given moment, and upon the condition of the heating sur- 
face, whether there will be an upward or downward cur- 
rent in the tubes near the back end of the boiler." 



CHAPTER X. 



EXTEKNALLY FIRED BOILERS. 

Cylinder Boilers — Safety and Economy of — Vertical Cylinder Boiler — 
The French or Elephant Boiler — Two-flue Boilers — Five-flue Boil- 
ers — Boilers fitted with six-inch lap Welded Flues — Test of a Flue 
Boiler — Tubular Boilers — Arrangement and number of Tubes — Pro- 
portions for Shells— Grate Areay— Coal required per hour — Tube 
Area — Evaporative Power of Tubular Boilers — Compound Tubular 
Boiler. 

Externally fired boilers — The simplest form of a boiler is 
a plain cylinder set in brick work. This type of boiler is 
largely used in sections of the country whore coal is cheap, 
or in the hi mber regions, where sawdust and slabs ave used 
as fuel. In many cases where fuel is abandant and cheap, 
the feed water hard and apt to form a troublesome scale, 
cylinder boilers recommend themselves as being at once 
easily managed, easily cleaned, offering, with the exception 
of the sphere, the strongest possible form to resist burst- 
ing, and affording the readiest facility for examination and 
repairs; and, for a given weight or efiiciency of heating 
surface, the lowest priced boiler that is now in the market. 

These boilers steam well, and prime less than any other 
form. In mining and lumber regions they are especial 
favorites, and it would be difficult to displace them, espe- 
cially if the feed water is impure. They are also exten- 
sively used at blast furnaces, and less so, perhaps, in rolling 
mills. 

An argument used against externally fired boilers is, 
that the plates immediately over the furnace are liable to 



EXTERNALLY FIRED BOILERS. 219 

become overheated, either by too hard firing or by the 
accumulation of scale in the boiler; the pressure being 
internal, the tendency to rupture being that of bursting. 
The plates are none too strong to begin with, and being 
further weakened by overheating they become dangerous 
in the extreme, and are thus liable to explode at any time 
when overworked. 

There is much of a showing of truth in the statement, 
but fortunately it has not been verified in actual experi- 
ence. That explosions of exernally fired boilers brought 
about by the overheating of plates has occurred, is not 
denied. Whether the disastrous effects are more or less 
.than that occasioned by the collapse of the main flue of an 
internally fired boiler does not concern ns. If the ques- 
tion be resolved to that of absolute, and not relative safety, 
and it were asked whether -any form of riveted boiler, 
either externally or internally fired, could be made abso- 
lutely safe, there could be but one answer, and that — no. 
It becomes then a matter of relative safety. This can be 
secured only by a careful selection of plates and the best 
proportions and workmanship. The writer has gone over 
this ground very carefully, and is of the opinion that, if 
iron is used having a tensile strength of not less than 
50,000 pounds, or steel having a tensile strength of 60,000 
to 65,000 pounds, the longitudinal seams double riveted, 
all the rivet holes carefully matching each other, and the 
workmanship good throughout, that the pressures given in 
.tables XLYII and XLIX are none 'too high; and if the 
boiler is properly fired and taken care of, there need be no 
apprehensions as to its safety. ^_ 

Cylinder boilers commonly range between thirty and 
forty-two inches in diameter, and in length from eight to 
twelve diameters. The great length given this type of 
boiler over those" fitted with flues or tubes is to present a 
greater surface for the absorption of the heat from the 



220 A TREATISE ON STEAM BOILERS. 

gases. These boilers are usually set in " batteries " of from 
two to six. The latter is too many, the former making 
a far better arrangement, and will also permit cleaning or 
repairs to be made without interfering with the others in 
use. 

The usual mode of setting these boilers is to have them 
suspended in the furnace. For this purpose special forg- 
ings or pieces of T iron are riveted to the upper portion of 
the shell, one-fourth the length of the boiler from each 
end, where two suspension bolts are to be used. If more 
than two, they are so disposed as to have each bolt bear 
its proportion of weight. These suspension bolts are car- 
ried up between a pair of wrought iron beams or castings » 
which span the furnace, and adjusted by means of nuts and 
washers to the required level. The writer does not, in 
general, recommend more than two points of suspension, 
on account of the distortion of the boiler, caused by the 
unequal heating of the lower and upper portions of the 
shell. 

An argument used against cylinder boilers is that, they 
are not economical in the use of fuel. There is much of 
truth in this assertion ; but less attention is, as a general 
thing, paid to the setting of cylinder boilers, and which 
will, in a measure, account for their lack of economy. As 
a rule, the furnaces are too large, as is also the space under 
the boiler and the openings leading to the chimney; the 
draft being regulated at the ash pit door in the fire room. 
This is far from the best way of getting the greatest evap- 
oration in a cylinder boiler. There should be a wall at the 
back end of the boiler similar to that shown in the 
engraving of tubular and flue boiler settings. Such a 
wall will compel a flow of gases from the furnace to keep 
in close contact with the shell of the boiler. Immediately 
back of the end of the boiler should be placed a damper, 
and should, by means of a rope or other device, be so 



CYLINDER BOILERS. 221 



arranged that it could be opened or closed at will. This 
damper should be so adjusted that the iiow of gases from 
the furnace shall only be that necessary to supply the burn- 
ing fuel with oxygen. This will be found to yield better 
results than keeping the damper wide open and regulating 
the supply of air through the ash pit doors. 

The following description, from Engineering, of the^ 
cylinder boilers of the Cambria Iron Company, Johnstown, 
Pa., by Mr. A. L HoUey, may be of interest to many : 
" The furnace is supplied with steam by eight cylinder 
boilers, e.ach sixty feet long and forty-eight inches in diam- 
eter. The boilers are set in pairs, each connected below 
on each outside sheet by short cross boilers, thirty inches 
in diameter and six feet long, with sixteen-inch connec- 
tions. The gases * are admitted at the ends of the boilers 
into combustion chambers, similar to those in the Player 
stoves, and thence they pass through flues under the boilers. 

" To provide for emergencies a firing grate, six feet 
square, is placed twenty feet from the ends of the boilers. 
Each pair of boilers is hung on wrought iron turned arches 
supported by side walls. The boilers are suspended by 
bolts resting on .spiral springs, and are perfectly free 
between the walls ; there is no trouble resulting from 
expansion and contraction. The cross boilers have each a 
branch, ten inches in diameter, extending through the side 
walls, with four-inch spaces all around them, the space 
being covered with loose plates of iron. The branches 
receive the feed water, and also serve to connect the blow 
ofi:*, which is inserted in the neck far enough to be bent, so 
as to reach the lowest point of the cross boiler. This 
arrangement enables each cross boiler to be blown off sep- 
arately. The feed pipe is ten inches in diameter, having 
connections with each cross boiler. The boilers are so 

'•'•The gases from the blast furnace, being principally carbonic oxide gas, may be used 
as fuel. B. 



222 



A TREATISE ON STEAM BOILERS.. 



arranged that any pair can be cut off for any purpose with- 
out interfering with the working of the furnace." 

Vertical cylinder boilers — Messrs. Douglas & Sons, Pitts- 
burg, Pa., have put in several of their patent vertical cylinder 
boilers in that city, and at Youngstown, 
Ohio, on a plan which may be new to 
many of the readers, but which prom- 
ises, from what the writer is able to learn, 
to be a success. Figure 52 shows the 
boiler arranged to receive the waste heat 
from a puddling furnace. The boiler 
itself is a plain cylindric vertical shell ; 
a short distance below the water line, 
say twelve inches, a hfead is inserted and 
another cylinder added of such height 
as may be needed for the steam room. 
This smaller cylinder is ten 



inches less in diameter than 
the larger, or twice the width 
of the lire brick built around 
the steam room, 
as shown in the 
engraving. The 
object of this fire 
brick ■ around 
the steam room 
is to prevent 
the intense heat 
from destroying the iron, as it is sure to do when not in 
contact with the water. Enough heat passes 'through the 
fire brick, however, to slightly superheat the steamj and is 
thus furnished the engines. perfectly dry. 

An opening is made in the side of the boiler at any 
convenient distance from the bottom and a special fitting 




THE FRENCH BOILER. 



223 



attached, through which the gauge cock pipes pass. These 
are, as usual, three in number. The first runs up to within 
six feet, the second to seven feet and the third to within 
eight feet of the top of the boiler. The steam pipe is also 
attached to this fitting, and passes up to within six inches 
of the top. 

The boiler is encased in a sheet iron stack large enough 
to be lined with four and a half inch brick wall, and leaves 
a five inch fire space between boiler and brick. The man 
hole is at the bottom of the boiler, and the blow off valve 
connected to the lower head of boiler. Bj this method of 
setting it is possible to work cold water into the boiler 
without injury, by introducing it below the heating surface. 
Scales or dirt do not adhere to the sides of the boiler, but 
fall to the bottom, from which they are easily removed. 

The French holier — This is also called the Elephant 
boiler. It is extensively used in France and on the conti- 
nent of Europe. The writer is not aware that any are in 




Figure 53. 

use in this country. This boiler is an assemblage of two 
or three smaller cylinder boilers and a large shell into one 
structure. It will be observed, by referring to figures 53 
and 54, that the lower cylinders or tubes are filled with water 
and almost wholly surrounded by heated gases. These lower 



224 



A TREATISE ON STEAM BOILERS. 




Figure 54. 



cylinders have suitable connections to 
permit a free and rapid circulation of 
water between them and the larger 
cylinder above. The number of lower 
cylinders varies from one to three, but 
commonly two. The particular boiler 
illustrated here is a representation of 
the one used in the famous experiments 
at Mulhouse, the principal dimensions 
being as follows: The main body of 
this boiler* is 20 feet 6f inches long 
by 3 feet 8.9 inches in diameter, and is 
made of half inch plates, except the ends, which are 0.55 
inch thick The three lower cylinders are 19.7 inches in 
diameter by 32 feet 9f inches long, and are made of 0.39 inch 
plates, while each communicates with the main body of the 
boiler by three connecting tubes. The grate is 4 feet 9-^ 
inches in width by 4 feet 9^^ inches long. This includes 
6.7 inches taken up by the bearings of the bars. Taking 
the effective length of the grate, 4 feet 2^^ inches, the area 
is 20.05 square feet. The heating surface of the boilers is 
607.6 square feet, divided as follows : 

SQUARE FEET. 

Surface exposed by main body of boiler 199.48 

Surface exposed by three lower cylinders 385.68 

Surface exposed by nine connecting pipes 22 44 



\ 



607.60 

The setting of this boiler is arranged as shown in the 
engraving, so that the products of combustion act first on 
the surfaces of the three lower cylinders, then return to 
the front end, along one side of the main cylinder, and 
finally pass to the chimney along the other side. This 
boiler was also provided with a "butterfly" damper, 
worked by a lever provided with a sector. The areas of 

'^Engineering, volume 21. 



THE FRENCH BOILER. 



225 



opening of the damper corresponding to each notch of the 
sector was measured and found to be as follows : 



Number of notch 


1 
0.325 


2 
0.394 


3 
0.533 


4 
0.812 


5 
1.161 


6 
1.509 


7 


Area in square feet for opening 


1.885 







The boiler was also supplied with the usual fittings. 

During the experiments a record was kept of the coal 
and water consumption, and observations were made of 
the temperatures of the gases entering the chimney, of the 
analysis of these gases, and of the quantity of water taken 
off, in suspension, by the steam. The following table gives 
the results obtained with both light and heavy firing : 

TABLE LXII. 

GIVING AN ABSTRACT OF RESULTS OBTAINED BY EXPERIMENTAL TESTS 

MADE WITH THE FRENCH, OR ELEPHANT BOILER, 

DESCRIBED ON PAGE 223. 



Coal consumed per day of eleven hours 

Net combustible consumed per day of eleven 
hours 

Water evaporated per day of eleven hours... 

Equivalent evaporation from and at 212° per 
pound of coal 

Equivalent evaporation from and at 212° per 
pound of net combustible 

Equivalent evaporation from and at 212° per 
hour, per square foot of heating surface... 

Weight of air supplied per pound of coal 
consumed 

Mean temperature of gases entering the 
chimney , 

(16) 



LIGHT 


HEAVY 


FIRING. 


FIRING. 


2,449 lbs. 


4,435 lbs. 


2,117 lbs. 


3,811 lbs. 


18,800 lbs. 


32,696 lbs. 


8.97 lbs. ■ 


8.60 lbs. 


• 10.37 lbs. 


10.02 lbs. 


3.28 lbs. 


5.71 lbs. 


14.89 lbs. 


14.37 lbs. 


425° 


563° 



226 



A TREATISE ON STEAM BOILERS. 



The above table shows a good rate of evaporation, but 
it does not surpass that of a good tubular, which can be 
furnished for a great deal less money for the boiler itself, 
and scarcely half as much for the setting in brick work. 

This boiler weighed, with its accessories, 31,900 pounds, 
and cost $2,141.22 for the boiler, and |580.80 for the set- 
ting, or a total cost of |2,722.02 



Flue boilers — The transition from a cylinder to a flue 
boiler is an easy and a natural one, and probably suggested 
itself as a means of utilizing the waste gases passing into 
the chimney. 

Two-flue boilers (flgure 55) are in very common use in 
this country, and rauge in diameter from thirty-six to forty- 
eight inches ; perhaps there are 
more forty-two inches in diam- 
eter than any other size. This 
style of boiler varies in length 
from ^YQ to eight diameters. The 
diameters of the flues approxi- 
mate very closely one-third of 
the diameter of the shell. This 
boiler has been long tried, and 
has stood the test well. It aflbrds 
good facilities for cleaning and 
inspection ; steams well and per- 
mits a good circulation of water. 
The following table (LXIII) gives the proportions used 
by the writer, and will be found to accord very closely with 
the best average practice. The heating surface is two- 
thirds of the circumference of the shell multiplied into its 
lenofth, to which is added the whole surface of the flues. 
The weights given are for one-quarter inch iron, in all 
cases, for the shells, and for the heads, as follows : 




Figure 55. 



TWO-FLUE BOILERS. 



227 



36 and 38 inches diameter f inch thick. 

40, 42, 44, 46 inches diameter ^inch thick. 

48 inches diameter ^ inch thick 

The weights include a 9X15 man hole plate above, and 
a hand hole, or smaller man hole plate, below the flues; 
also, the necessary stays and braces for the heads. The 
weights do not include a dome, or fixtures of any kind. 

These tabular weights agree so closely to the average 
actual weights of the boilers after completion that they 
will be found sufficiently accurate to use in making con- 
tracts. 

TABLE LXIII. 

SHOWING PROPORTIONS, HEATING SURFACE AND HORSE POWER OF 

TWO-FLUE BOILERS. 



SHELL. 


FLUES. 


DIAME- 
TER. 


LENGTH. 


DIAME- 
TER. 


THICK- 
NESS. 


INCHES. 


FEET. 


INCHES. 


INCHES. 


36 


14 


12 


i 




16 


12 


1 
1 




18 


12 


i 




20 


12 


i 


38 


14 


12 


k 




16 


12 


i 




18 


12 


i 




20 


12 


i 


40 


16 


14 


i 




18 


14 


J 




20 


14 


i 




22 


14 


i 




24 


14 


i 



HEATING 

SURFACE OF 

^ SHELL AND 

WHOLE OF 

FLUES. 



SQUARE FEET. 
176 

201 
227 
252 
181 
206 
233 
259 
229 
256 
284 
314 
342 



APPROXIMATE 

WEIGHT OF 

i SHELL. 



POUNDS. 
3,238 

3,619 
4,000 
4,381 
3,364 
3.757 
4,150 
4,548 
4.117 
4,553 
4,987 
5,424 
5,860 



HORSE 

POWER 

AT 

12 FEET. 



14.7 

16.8 
18.9 
21.0 
15.0 
17.2 
194 
21.6 
19.1 
21.3 
23.7 
26.2 
28.5 



228 



A TKEATISE ON STEAM BOILERS. 



TABLE LXIII— Continued. 



SHELL. 


FLUES. 


HEATING 




TTOR9P. 










SURFACE OF 

f SHELL AND 

WHOLE OF 

FLUES. 


APPROXIMATE 

WEIGHT OF 

I SHELL. 


POWER 


DIAME- 
TER. 


LENGTH. 


DIAME- 
TER. 


THICK- 
NESS. 


AT 
12 FEET. 


INCHES. 


FEET. 


INCHES. 


INCHES. 


SQUARE FEET. 


POUNDS. 




42 


16 


14 


i 


235 


4,243 


19.6 




18 


14 


i 


264 


4,700 


22.0 




20 


14 


i 


294 


5,157 


24.5 




22 


14 


i 


323 


5,614 


26.9 




24 


14 


i 


352 


6,071 


29.3 


44 


16 


16 


i 


257 


^ 4,561 


21.4 




18 


16 


i 


288 


5,046 


24.0 




20 


16 


i 


322 


5,531 


26.8 




22 


16 


i 


353 


6,016 


29.4 




24 ' 


16 


i 


386 


6,501 


32.2 


46 


16 


17 


I 


270 


4,800 


22.5 




18 


17 


i 


305 


5,311 


25.4 




20 


17 


i 


339 


5,822 


28.3 




22 


17 


i 


373 


■ 6,333 


31.1 




24 


17 


1 
4 


407 


6,844 


33.9 




26 


17 


i 


441 


7,355 


36.8 


48 


16 


18 


I 


284 


5,031 


23.7 




18 


18 


i 


321 


5,566 


26.8 




20 


18 


i 


356 


6,101 


29.7 




22 


18 


i 


392 


6,636 


32.7 




24 


18 


i 


427 


7,171 


35.6 




26 


18 


I 


464 


7,706 


38.7 




28 


18 


i 


499 


8,241 


41.6 




30 


18 


i 


533 


8J66 


44.4 



FIVE-FLUE BOILERS. 229 



The thickness of flues is given in the table as ^ inch in 
all cases. For diameters greater than 14 inches, -^^ iron 
may be used with advantage. It is not an easy matter to 
make thick flues of small diameters, and, in consequence, 
they seldom exceed J inch, except for very high pressures. 
The sheets are usually made for 30 inch lengths. How 
much a circumferential seam of rivets, together with the 
double thickness of iron, adds to the strength of the 
flue to resist collapse, when occurring at every 30 inches 
of its length, is not known to the writer, and he is not 
aware that any experiments of that kind on long tubes, 
for different thickness of metal, have ever been made. 

The following table gives the thickness of flues used 
by the boiler makers at Pittsburg, Pa., and allowed by 
the Government Inspectors for boilers, although it is 
known that they are intended for river service, where 150 
lbs. to the square inch is not uncommon in emergencies : 

DIAMETER OF FLUE. THICKNESS. 

16 inches 31 inch. 

15 inches 29 inch. 

1 4 inches 27 inch . 

13 inches 25 inch. 

12 inches 23 inch. 

11 inches 21 inch. 

10 inches 1 9 inch . 

9 incnes ITinch. 

8 i tiches 15 inch. 

7 inches '. 13inch. 

6 inches 11 inch. 

Mveflae boilers — Sometimes the flues are decreased in 
diameter and increased in number for the same diameter 
of shell in order to carry a higher pressure than would 
be allowed in a two flue boiler. It is a common practice, 
in some sections of the country, to make a boiler with flve 
flues, as shown in flgure 56. They are shown in the en- 
graving as being all of the same diameter. The flues are 



230 



A TREATISE ON STEAM BOILERS. 



often made of several diameters for the same boiler, and 
will not vary much from sizes given below : 

DIAMETER OF BOILER. DIAMETER OF FLUES. 

44 inches I o ~ ^o ^""^u^'' 

(3 — 8 inches. 

(1 — ^13 inches. 
46 inches ^2 — • 9 inches. 

(2 — 8 inches. 

(1 — 12 inches. 
48 inches -^2 — ]0 inches. 

(2 — 8 inches. 

il — 14 inches. 
2 — 10 inches. 
2 — 8 inches. 



The above was intended for lap riveted flues. It is now 
possible to get lap welded flues, of large diameter; these 

being free from joints, perfectly 
cylindrical, and practically uni- 
form in quality, are recommend- 
ed as being in all respects supe- 
rior to the ordinary riveted flue, 
except the strength which the 
lap riveted joints gives the flues 
to resist collapse. When these 
lap welded flues are used, it is, 
on the whole, preferable to make 
the diameters the same for all the 
flues, instead of having two or 
three sizes, as given above. 
The following table (LXIY) gives the proportions, 
weight, etc., including all the details mentioned in connec- 
tion with the two flue boilers. As lap welded flues are not 
sold by weight, two columns are given in the table, in order 
to figure the shell by the pound and the tubes by the foot. 
The total weight is given for shipping or other purposes. 




Figure 56. 



FIVE-FLUE BOILERS. 



231 



TABLE LXIV. 

SHOWING PROPORTIONS, HEATING SURFACE AND HORSE POWER OF 

FIVE-FLUE BOILERS. 



SHELL. 




HEATING 




WEIGHT, 










FLUES. 
DIAME- 
TER. 


SURFACE, 
f SHELL 

AND 

WHOLE OF 

FLUES. 








HORSE 


DIAME- 
TER. 


LENGTH. 


SHELL. 


FLUES. 


TOTAL. 


POW EK 

AT 

12 FEET. 


INCHES. 


FEET. 


INCHES. 


SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




36 


12 


7 


185 


1,933 


746 


2,679 


15.4 




14 


7 


218 


2,161 


871 


3,032 


18.2 




16 


7 


246 


2,388 


995 


3,383 


20.5 


38 


12 


7 


190 


2,045 


746 


2,791 


15.8 




14 


7 


223 


2,286 


871 


3,157 


18.6 




16 


7 


251 


2,527 


995 


3,522 


20.9 




18 


7 


284 


2,769 


1,119 


3,888 


23.7 


40 


12 


8 


208 


2,139 


907 


3,046 


17.3 




14 


8 


242 


2,392 


1,058 


3,450 


20.2 




16 


8 


281 


2,645 


1,209 


3,854 


23.4 




18 


8 


314 


2,897 


1,360 


4,257 


26.2 




20 


8 


348 


3,149 


1,511 


4,660 


29.0 


42 


14 


9 


268 


2.506 


1,260 


3,766 


22.3 




16 


9 


307 


2,771 


1,440 


4,211 


25.6 




18 


9 


346 


3,034 


1,620 


4,654 


28.8 




20 


9 


385 


3,298 


1,800 


5,098 


32.1 




22 


9 


424 


3,562 


1,980 


5,542 


35.3 


44 


14 


10 


293 


2,617 


1,554 


4,171 


24 4 




16 


10 


333 


2,893 


1,775 


4,668 


27.8 




18 


10 


373 


3,169 


1,997 


5,166 


31.1 




20 


10 


414 


3,445 


2,219 


5,664 


34.5 




22 


10 


459 


3,721 


2,441 


6,162 


38.3 




24 


10 


499 


3,997 


2,663 


6,660 


41.6 



232 



A TREATISE ON STEAM BOILERS. 



TABLE LXIV— Continued. 



SHELL. 




HEATING 




WEIGHT. 










FLUES. 
DIAME- 
TER. 


SURFACE, 

f SHELL 

AND 

WHOLE OF 

FLUES. 








HORSE 


DIAME- 
TER. 


LENGTH. 


SHELL. 


FLUES. 


TOTAL. 


POWER 

AT 

12 FEET. 


INCHES. 


FEET. 


INCHES. 


SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




46 


16 


10 


338 


3,048 


1J75 


4,823 


28.2 




18 


10 


380 


3,339 


1,997 


5,336 


31.7 




20 


10 


421 


3.630 


2,219 


5,849 


35.1 




22 


10 


467 


3,921 


2,441 


6,362 


38.9 




24 


10 


508 


4,212 


2,663 


6,875 


42.3 


48 


16 


10 


344 


3,173 


1,775 


4,948 


28.7 




18 


10 


386 


3,476 


1,997 


5,473 


32.2 




20 


10 


428 


3,779 


2,219 


5,998 


.35.7 




22 


10 


474 


4,082 


2,441 


6,523 


39.5 




24 


10 


516 


4,385 


2,663 


7,048 


43.0 



Six inch flue boiler — Another arrangement of lap welded 
flues, and one which is already very popular in some sec- 
tions of the country, is to make a boiler with as man}^ six 
inch flues as it will contain below the upper limit of tube 
surface. Figure 57 shows an end elevation of a forty-four 
inch boiler fitted with nine flues six inches in diameter, 
riveted at each end to flanged heads. If the heads are 
made of the best flange iron there is no difiiculty in flang- 
ing the flue holes within three inches of each other. 
Owing to the great difiiculty in keeping the heads flat 
machine flano^ino: is recommended. It is also recom- 
mended that one head be flanged in and the other flanged 
out. The flue holes shown in figure 57 are said to be 
flanged out; that is, they are flanged in the opposite direc- 



SIX-INCH FLUE BOILERS. 



233 



tion to the flange intended for the shell. To those who 
have never made such a* boiler it would appear impractic- 
able to properly rivet the flues at the rear end, or in the 
head containing the flue holes flanged in. A few special 
tools for holding the rivets in place are needed, and, per- 
haps, a few special riveting hammers. 

Begin with the bottom flues, insert the rivets from the 
inside of the boiler, and rivet them on the inside of the 
flue ; this can be done with little difficulty from the out- 
side of the boiler. The rivets should be h-alf an inch in 
diameter for six inch flues. 

This boiler steams well, and is easily kept clean. The 
following table gives the propor- 
tions, as used by the writer, to- 
gether with the heating surface, 
etc. The thickness of shell for 
all boilers up to and including 
forty-eight inches is one-quarter 
inch. The fifty-four and sixty 
inch shells are five-sixteenths 
inch, with five-eighths inch heads. 
All shells double riveted. The 
weights include the necessary 
stays, but no dome or fixtures of 
any kind. No lengths are given 
for boilers more than twenty feet long, for the reason that 
manufacturers advance the price on the whole length of 
tubes when they exceed twenty feet. This advance is so 
out of proportion to the ordinary market value of boilers 
that it does not " pay" to use them. 




Figure 57. 



234 



A TREATISE ON STEAM BOILERS. 



TABLE LXV. 

SHOWING PROPORTIONS, HEATING SURFACE AND HORSE POWER OF 
BOILERS FITTED WITH SIX-INCH LAP WELDED FLUES. 



SHELL. 




HEATING 




WEIGHT. 










NUMBER 

OF 
FLUES. 


SURFACE, 

f SHELL 

AND 

WHOLE OF 

FLUES. 








HORSE 


DIAME- 
TER. 


LENGTH. 


SHELL. 


FLUES. 


TOTAL. 


POWER 

AT 

12 FEET. 


INCHES. 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




42 


12 


6 


201 


2,242 


673 


2,915 


16.7 




14 


6 


235 


2,506 


785 


3,291 


19.6 




16 


6 


268 


2,770 


897 


3,667 


22.3 




18 


6 


302 


3,034 


1,009 


4,043 


25.2 




20 


6 


336 


3,298 


1,122 


4,420 


28.0 


44 


12 


9 


262 


2,341 


1,009 


3,350 


21.8 




14 


9 


306 


. 2,617 


1,178 


3,795 


25.5 




16 


9 


349 


2,893 


1,346 


4,239 


29.1 




18 


9 


392 


3,169 


1,514 


4,683 


32 7 




20 


9 


437 


3,445 


1,682 


5,127 


36.4 


46 


12 


10 


285 


2,466 


1,122 


3,588 


23.8 




14 


10 


332 


2,757 


1,308 


4,065 


27.7 




16 


10 


379 


3,048 


1,495 


4,543 


31.6 




18 


10 


428 


3,339 


1,682 


5.021 


35.7 




20 


10 


475 


3,630 


1,869 


5,499 


39.6 


48 


12 


12 


327 


2,568 


1,316 


3,914 


27.3 




14 


12 


381 


2,871 


1,570 


4,441 


31.2 




16 


12 


436 


3,174 


1,794 


4,968 


36.3 




18 


12 


490 


3,477 


2,019 


5,496 


40.8 




20 


12 


545 


3,780 


2,243 


6,023 


45.4 



SIX-INCH FLUE BOILERS. 



235 



TABLE LXV— Continued. 



■ SHELL. 


NUMBER 
OF 


HEATING 

SURFACE, 
f SHELL 


AVEIGHT. 


HORSE 














DIAME- 
TER. 


LENGTH. 


FLUES. 


AND 

WHOLE OF 
FLUES. 


SHELL. • 


FLUES. 


TOTAL. 


AT 
12 FEET. 


INCHES. 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




54 


14 


14 


440 


4,276 


1,832 


6,108 


36.7 




16 


14 


503 


4,708 


2,094 


6,802 


41.9 




18 


14 


566 


5,141 


2,355 


7,496 


47.2 




20 


14 


628 


5,573 


2,617 


8,190 


52.3 


60 


14 


18 


543 


5,077 


2,355 


7,432 


45.3 




16 


18 


620 


5,553 


2,692 


8,245 


51.7 




]8 


18 


697 


6,029 


3,028 


9,057 


58.1 




20 


18 


774 


6,505 


3,365 


9,870 


64.5 



The above examples suffice to show the combinations^ 
proportions, heatino^ surface and weights of flue boilers in 
general use. It is possible to make so many combinations 
by using flues of several diameters in the same boiler that 
it would unnecessarily cumber the book with tables, if they 
were all to be taken into account. The weights and heat- 
ing surface for any other style of flue boilers than those 
given may be easily determined by using the flgures already 
furnished in the tables. 

The following test made by Isaac Y. Holmes, M.E., 
Cleveland, Ohio, shows results somewhat over the average 
for flue boilers. There is no doubt that much of this is 
due to the superior setting of the boilers, the exceptional 
richness of the coal, and perfect combustion. The furnace 
will be described in the chapter on boiler settings : 



236 A TREATISE ON STEAM BOILERS. 

These tests were made at the Soldiers' Home, near Day- 
ton, Ohio, on the twenty-seventh and twenty-eighth ot 
March, 1877. 

Each boiler was fifty-four inch diameter of shell, twenty- 
eight feet long, four six-inch flues, two ten-inch flues, no 
steam dome ; the feed water was delivered through a mud 
drum attached to the rear. 

Each trial was a continuous run of twelve hours, and 
was conducted as follows : 

The boiler was connected at its regular duty, with steam 
pressure at fifty pounds by gauge attached to shell, and the 
level of water at standard mark attached to glass water 
gauge. 

. At the time noted, all the burning fuel was drawn from 
the furnace and the ash pit cleaned. Then the furnace 
was stocked with coal from that weighed for the test, and 
the trial commenced. 

All coal used during the trial was weighed and deliv- 
ered in one hundred pound lots. 

All water delivered was weighed before it was discharged 
into feed tank, and at commencement of test was on a level 
with gauge line. The temperature of the same was observed 
and entered on the log every fifteen minutes. 

At the termination of the twelve hours all the burning 
fuel on the grates was removed and extinguished, and all 
unburned fuel credited back, while the clinker and ashes 
were weighed dry, and the water, both in the boiler and 
feed tank, w^as left at the standard marks. 

Summary of i^esults — Condition of atmosphere the same 
on both days of trial: 

DUTY. NO. 1 BOILER. NO. 2 BOILER. 

The same on each boiler Heating buildings. 

COAL. 

The same kind for both trials Youghiogheny lump. 



TEST OF A FLUE BOILER. 237 

DURATION. NO. 1 BOIIiER. NO. 2 BOILER. 

Continuous firing 12 hours. 12 hours. 

OBSERVATIONS. 

Total amount water weighed to boiler. .28, 5 21 lbs. 30,423 lbs. 

Total amount coal weighed to furnace.. 3,433 lbs. 3,700 lbs. 

Total amount ashes weighed dry 193 lbs. 278 lbs. 

Total amount combustible 3,240 lbs. 3,422 lbs. 

Average temperature feed water in 

tank 106° 118° 

Average temperature back connection. 700° 659° 

Average temperature uptake 446° 476° 

Average temperature air in pipe 107° 107° 

Average temperature air in furnace not taken. 495° 

Average pressure steam at boiler 48 lbs. 46.5 lbs. 

Average pressure steam at main 18.5 lbs. 17 lbs. 

Average percentage water in steam .126 .053 

PERFORMANCE. 

Coal per hour 286 lbs. 308.33 lbs. 

Combustible per hour 270 lbs. 285 lbs. 

Water per hour , 2,380 lbs. 2,535 lbs. 

Pounds of water evaporated at 48 lbs. 

pressure and temperature at 106° 

per one pound of coal 8.31 

Pounds of water evaporated at 46.5 

lbs. pressure and temperature of 

118° per one pound of coal 8.22 

Equivalent evaporation from pressure 

of atmosphere and temperature of 

212° per one pound of coal 9.43 9.23 

. Equivalent evaporation from pressure 

of atmosphere and temperature 

of 212° per one pound combustible, 9.988 9.983 

Conclusions — The evaporation of over nine pounds of 
water by the combustion of one pound of coal, with a six 
flued boiler, is a strong proof of the economy and effici- 
ency of the Butman furnace, while a close observation of 
its working showed the combustion was at all times very 
complete. No smoke evolved by the distillation of the 
fuel in the furnace, but clear heated gases, which flowed 



238 



A TREATISE ON STEAM BOILERS. 



off underneath and along the sides of the boiler, and from 
the top of the stack could only be seen the quivering pro- 
ducts of combustion floating off into the atmosphere, there 
being no color or indication of smoke whatever. 




Tabular boilers — This type of boiler is so well known 
as to need little or no description. 

Perhaps no other kind of boiler has had such an exten- 
sive sale as this ; if it is to be 
used where the feed water is pure 
and clean, it is then, probably, 
the " best boiler for the money " 
in the market, but it is not the 
boiler to be recommended in all 
cases. The writer never hesi- 
tates to recommend it in cases 
where the feed water contains no 
lime or other substances which 
will form scale ; and does not 
recommend it where the water is 
bad, unless the means for pre- 
venting the scale are known to be efficient. There is 
quite a diversity of opinion in regard to proportion- 
ing tubular boilers. There are those who advocate 
length rather than diameter ; others, advocating the re- 
verse. ITo doubt much of the confusion on this point 
arises from a lack of exact knowledge as to the relative 
values of shell and tube heating surface. It is just here 
that the error in reckoning horse power by extent of heating 
surface, rather than by efficiency, becomes fully apparent. 
There is a prevailing notion that the power of a tubular 
boiler may be indefinitely extended, by simply increasing 
the number of tubes in the shell. This is a mistake. Too 
many tubes, especially if of small diameters, may so pre- 
vent the circulation of the water in the boiler as to dimin- 



FlGURE 58. 



HORIZONTAL TUBULAR BOILERS. 239 

ish, instead of increase the evaporation. It thus has the 
effect to induce priming, and may lead to the overheat- 
ing of the plates immediately over the grates. 

The ratio of tube area to grate surface has something 
to do with the fixing of the maximum number of tubes for 
any given boiler. The grate area being known, then, one- 
seventh of this area sufiices for the tube area, as the largest 
admissible under the severest firing in stationary boilers 
with chimney draft, and for forced draft, if the coal burned 
per square foot of grate does not exceed twenty pounds 
per hour. This rate of combustion is in excess of ordinary 
practice, the common rate being not far from fifteen 
pounds per hour for each square foot of grate. For this, 
one-twelfth of the grate area will suffice for the maximum 
tube area. 

The length of tubes is practically limited to twenty feet, 
as manufacturers do not carry them in stock and charge 
an additional price per foot for the whole tube when made 
to order of a greater length. Tubular boilers are seldom 
made longer than sixteen feet if the tubes are less than four 
inches in diameter. When ^ve to -six inches in diameter 
they may then be made twenty feet long. Casual observa- 
tions made on the steaming capacity and temperature of 
escaping gases show that in tubular boilers having lengths 
of twelve, fourteen and sixteen feet, and with ordinary 
slow firing, that the two former are to be preferred to the 
latter length for tubes three inches in diameter. If a forced 
draft is employed, then three inch tubes, sixteen feet long, 
may be used with advantage if a damper is placed in the 
chimney so as to slightly increase the pressure of the gases 
flowing through the tubes. 

The following table (LXYI) gives the greatest number 
of tubes which may be inserted in boiler heads for the 
diameters given, the tubes to be arranged in vertical rows 
as shown in figure 59, and have a clear space between each 



240 



A TREATISE ON STEAM BOILERS. 



row of one-third the diameter of the tube. The top of 
the upper row of tubes is approximately 
three-iifths of the diameter of the boiler. 
„ In some cases, however, the tubes are car- 
ried a little higher, in order to prevent the 
end tubes in some ot the lower rows from 
*:^S^^ crossing within the line drawn for the min- 
FiGURE 59. imum water space. In no case does this 
change equal the half diameter of the tube. By arranging 
the end tubes in the bottom rows a little differently, the 
exceptions noted above may be remedied, but no particular 
objection exists to their remaining where they are. 




TABLE LXVL 



SHOWING THE GREATEST NUMBER OF TUBES WHICH MAY BE PUT IN A 
GIVEN HEAD (SUBJECT TO THE CONDITIONS STATED ABOVE 



DIAM- 






DIAMETER OF 


rUBES. 






HAND 


ETER OF 
















OR 


BOILER. 


3 


H 


H 


3f 


4 


^ 


5 


MAN HOLE. 


36 


26 


23 


19 


20 


16 


12 


10 


6x8 


38 


32 


23 


21 


20 


18 


12 


14 


6x8 


40 


34 


34 


25 


23 


20 


14 


14 


6x8 


42 


45 


38 


32 


26 


25 


20 


18 


6x8 


44 


48 


36 


32 


30 


25 


20 


16 


6x8 


46 


42 


38 


34 


28 ■ 


23 


21 


16 


8x32 


48 


50 


38 


36 


30 


26 


21 


18 


8x12 


50 , 


55 


42 


38 


34 


30 


23 


20 


8x12 


52 


57 


50 


48 


38 


32 


26 


21 


8x12 


54 


66 


55 


48 


38 


36 


28 


21 


8x12 


56 


72 


57 


55 


48 


41 


32 


23 


8x12 


58 


74 


66 


55 


48 


45 


32 


28 


8x12 


60 


80 


68 


62 


55 


46 


36 


30 


8x12 



HORIZONTAL TUBULAR BOILERS. 241 

Provision is made in this table for lower hand and man 
hole plates in all the boilers. The size for 36 to 44 inch 
boilers, inclusive, is 6X8 inches, and from 46 to 60 inches, 
8X12 inches No tube is located nearer than 2 inches to 
the shell for diameter 36 to 44 inches, and none nearer than 
2J inches from 46 to 52 inches, and none nearer than 3 
inches from 54 to 60 inches diameter of boiler. The diam- 
eter of the boiler is that of the inside in all cases. 

This table does not allow for a middle space up through 
the center of the boiler, as shown in figure 60. If the 
tubes are not placed nearer together than 
i their diameter, and the clear space 
between the tube and the shell of the 
boiler is not less than that given on page 
240, and the water does not contain im- 
purities which will form scale, it is alto- 
gether probable that the circulation will figure eo. 
be ample to furnish dry steam, with the number and 
arrangement of tubes which the table calls for. 

If the water is hard and will form scale, then the space 
shown in figure 60 should be allowed, because incrustation 
will gradually close the distance between the tubes and 
prevent proper circulation. This will lessen the number 
of tubes three to six. In some of the boilers, a row of 
tubes comes in the center ; and in others, a space, so that 
it will be necessary to re-arrange the tubes. The distance 
apart from tube to tube, in the central space in the boiler, 
may properly be fixed by the diameter of the shell. 

The following distances may be varied to suit circum- 
stances, but will be found to be ample, in any ordinary case, 
for tubes less than four inches diameter : 

(17) 




242 A TREATISE ON STEAM BOILERS. 

DIAMETER OF BOILER. DISTANCE APART. 

30 inches 2 inches. 

38 inches 2| inches. 

40 inches 2f inches. 

42 inches... 3 inches. 

44 inches 3| inches. 

• 46 inches 3| inches. 

48 inches 4 inches. 

50 inches 4f inches. 

52 inches....' 4f inches. 

54 inches 5 inches. 

56 inches 5| inches. 

58 inches 5f inches. 

60 inches • 6 inches. 

Tubes four inches in diameter and over, when simply 
expanded in the heads, are not generally put in shells less 
thanforty-eight inches in diameter. If the space, as given 
above, does not interfere with the locating of the desired 
number of tubes, it may be retained. In case it should, the 
distance may be shortened a little, on account of the 
greater distance apart of the tubes themselves over those 
of smaller diameter. 

The next table (LXYII) shows the proportions, heating 
surface, weight and horse power of three-inch tubular 
boilers. Boilers, thirty-six to forty-four inches inclusive, 
have a 6X8 hand hole below the tubes; from forty-six to 
sixty inches, an 8X12 man head similarly fitted. All the 
boilers have a 9X15 man head above the tubes. The 
weights do not include a dome or fixtures of any kind, but 
do include all necessary stays and bracing. 

The thickness of shell is one-quarter inch, from thirty- 
six to forty- eight inches inclusive, and five-sixteenths inch 
from fifty to sixty inches. The thickness of heads for 

36 and 38 inches diameter is f inch. 

40 to 46 inches diameter is ^ inch. 

48 to 52 inches diameter is *. J inch. 

54 to 56 inches diameter is ^ inch. 

58 to 60 inches diameter is # inch. 



THREE-INCH TUBULAR BOILERS. 



243 



If the fifty-eight and sixty-inch boilers are to carry 
more than one hundred and twenty-five pounds of steam, 
they should be made of steel, rather than increase the 
thickness of the shell. Longitudinal seams to be double 
riveted in all cases. 



TABLE LXVII. 

SHOWING PROPORTIONS, HEATING SURFACE, WEIGHT AND HORSE POWER 
OF TUBULAR BOILERS FITTED WITH THREE-INCH TUBES. 



SHELL. 


NUMBER 


HEATING 
SURFACE, 
3^ SHELL 


WEIGHT. 


HORSE 
POWER 


DIAME- 
TER. 


LENGTH. 


OF 
TUBES. 


AND 

WHOLE OF 

TUBES. 


SHELL. 


TUBES. 


TOTAL. 


AT 
15 FEET. 


INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




36 


8 


26 


213 


1,478 


693 


2,171 


14.2 




10 


26 


267 


1,705 


867 


■ 2,572 


17.8 




12 


26 


320 


1,933 


1,040 


2,973 


21.3 




14 


26 


374 


2,161 


1,213 


3,374 


24.9 




16 


26 


428 


2,389 


1,387 


3,776 


28.5 


38 


8 


32 


254 


1,563 


853 


2,416 


16,9 




10 


32 


317 


1,804 


1,067 


2,871 


21.1 




12 


32 


380 


2,045 


1,280 


3,325 


25.3 




14 


32 


443 


2,286 


1,493 


3,779 


29.5 




16 


32 


506 


2,527 


17,07 


4,234 


33.7 


40 


8 


34 


269 


1,632 


907 


2,539 


17.9 




10 


34 


336 


1,885 


1,133 


3,018 


22.4 




12 


34 


403 


2,138 


1,360 


3,498 


26.9 




14 


34 


470 


2,391 


1,587 


3,978 


31.3 




16 


34 


537 


2,644 


1,813 


4,457 


35.8 


42 


10 


45 


426 


1,978 


1,500 


3,478 


28.4 




12 


45 


512 


2,242 


1,800 


4,042 


34.1 




14 


45 


598 


2,506 


2,100 


4,606 


39.9 




16 


45 


684 


2,770 


2,400 


5,170 


45.6 



244 



A TREATISE ON STEAM BOILERS. 



TABLE LXVII— Continued. 



SHELL. 


NUMBER 
OF 


HEATING 
SURFACE, 
"3" SHKLLf 


WEIGHT. 


HORSE 
POWER 




















AND 








AT 


DIAME- 
TER. 


LENGTH . 


TUBES. 


WHOLE OF 
TUBES. 


SHELL. 


TUBES. 


TOTAL. 


15 FEET. 


inches 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




44 


10 


48 


454 


2,065 


1,600 


3,665 


30.3 




12 


48 


544 


2,341 


1,920 


4.261 


36.3 




14 


48 


634 


2,617 


2,240 


4,857 


42.3 




16 


48 


725 


2,893 


2,560 


5,453 


48.3 




18 


48 


816 


3,169 


2,880 


6,049 


54.4 


46 


10 


42 


410 


2,174 


1,400 


3,574 


27.3 




12 


42 


492 


2,465 


1,680 


4,145 


32.8 




14 


42 


575 


2,756 


1,960 


4,716 


38.3 




16 


42 


657 


3,047 


2,240 


5,287 


43.8 




18 


42 


739 


3,338 


2,520 


5,858 


49.3 


48 


10 


50 


477 


2,267 


1,667 


3,934 


31.8 




12 


50 


572 


2,569 


2,000 


4,569 


38.1 


• 


14 


50 


667 


2,871 


2,333 


5,204 


44.5 




16 


50 


763 


3,173 


2,667 


5,840 


50.9 




18 


50 


859 


3,476 


3,000 


6,476 


57.3 




20 


50 


954" 


3.778 


3,333 


7,111 


63.6 


50 


10 


55 


519 


3,009 


1,833 


4,842 . 


34.6 




12 


55 


623 


3,410 


2,200 


5,610 


41.5 




14 


55 


727 


3,811 


2,567 


6,378 


48.5 




16 


55 


831 


4,212 


2,933 


7,145 


55.4 




18 


55 


934 


4,613 


3,280 


7,893 


6^2.3 




20 


55 


1,038 


5,014 


3,666 


8,680 


69.2 


52 


12 


57 


646 


3,572 


2,280 


5,852 


43.1 




14 


57 


754 


3,988 


2,660 


6,648 


50.3 




16 


57 


862 


4,404 


3,040 


7,444 


57.5 




18 


57 


969 


4,820 


3,420 


8,240 


64.6 




20 


57 


1,077 


5,236 


3,800 


9,036 


71.8 



THREE-INCH TUBULAR BOILERS. 



245 



TABLE LX VII— Continued. 



SHELL, 


NUMBER 
OF 


HEATING 
SURFACE, 
f SHELL 


WEIGHT. 


HORSE 
POWER 














DIAME- 
TER. 


LENGTH. 


TUBES. 


AND 

WHOLE OF 

TUBES. 


SHELL- 


TUBES. 


TOTAL. 


AT 
15 FEET. 


INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




54 


12 


66 


735 


3,844 


2,640 


6.484 


49.0 




14 


66 


858 


4,276 


3,080 


7,356 


57.2 




16 


66 


980 


4,708 


3,520 


8,228 


65.3 




18 


66 


1,102 


5,140 


3,960 


9,100 


73.5 




20 


66 


1,224 


5,573 


4.400 


9,973 


81.6 


56 


12 


72 


796 


4,017 


2,880 


6,897 


53.1 




14 


72 


929 


4,464 


3,360 


7,824 


61.9 




16 


72 


1,062 


4,911 


3,840 


8,751 


70.8 




18 


72 


1,194 


5,358 


4,320 


9,678 


79.6 




20 


72 


1,326 


5,805 


4,800 


10,605 


88.4 


58 


12 


74 


8]8 


4,300 


2,960 


7,260 


54.5 




14 


74 


955 


4,762 


3,453 


8,215 


63.7 




16 


74 


1,091 


5,224 


3,947 


9.171 


72.7 




18 


74 


1,227 


5,686 


4,440 


10,126 


81.8 




20 


74 


1,364 


6,148 


4,933 


11,081 


90.9 


60 


12 


80 


880 


4,601 


3,200 


7,801 


58.7 




14 


80 


1,027 


5,077 


3,733 


8,810 


68.5 




16 


80 


1,174 


5,553 


4,267 


9,820 


78.3 




18 


80 


1,320 


6,029 


4,800 


10,829 


88.0 




20 


80 


1,467 


6,505 


5,333 


11,838 


97.8 



In some of the larger boilers in the above table the 
lengths are carried out to twenty feet. The writer never 
made a three-inch tubular boiler of that length, neither 
does he know of any in use, and would not, from data he 
now has relating to sixteen feet lengths, recommend twenty 



246 



A TREATISE ON STEAM BOILERS. 



feet, except in cases where a force blast is used and the 
combustion complete. It would require a careful adjust- 
ment of tube to grate area, and there must be coal enough 
burned on the grate to insure the tubes being completely 
filled with gases at all times. Ordinarily, it is better to 
keep the length at sixteen feet than to go beyond it. 

TABLE LXVIII. 

SHOWING THE WIDTH AND LENGTH OF GRATES, AND THE AREA IN 
SQUARE FEET, AS USUALLY SUPPLIED TUBULAR AND FLUE BOILERS. 
ALSO, THE AMOUNT OF COAL REQUIRED PER HOUR WHEN BURNED 
AT THE RATE OF 12, 14, 16, 18, 20 POUNDS PER SQUARE FOOT OF GRATE 
PER HOUR. 



DIAME- 




GRATE. 






COAL REQUIRED PER HOUR. 




TER 


















OF 


















BOILER. 


WIDTH. 


LENGTH 


AREA. 


12 LBS. 


14 LBS. 


16 LBS. 


18 LBS. 


20 LBS. 


INCHES. 


INCHES. 


INCHES. 


SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 


POUNDC. 


POUNDS. 


36 


45 


48 


15.0 


180 


210 


240 


270 


300 


38 


47 


48 


15.7 


188 


220 


251 


283 


. 314 


40 


49 


48 


16.3 


196 


228 


261 


293 


326 


42 


51 


52 


18.4 


221 


'258 


294 


331 


368 


44 


53 


52 


19.1 


229 


267 


306- 


344' 


382 


46 


55 


52 


19 9 


239 


279 


318 


358 


398 


48 


57 


52 


20.6 


247 


288 


329 


371 


412 


50 


59 


60 


24.6 


295 


344 


394 


443 


492 


52 


61 


60 


25.4 


305 


856 


406 


457 


508 


54 


63 


60 


26.3 


316 


368 


421 


473 


526 


56 


65 


72 


32.5 


390 


455 


520 


585 


650 


58 


67 


72 


33.5 


402 


469 


536 


603 


670 


60 


69 


72 


34.5 


414 


483 


552 


621 


690 



The above table gives the sizes of grates usually 
supplied with tubular boilers, by the writer, when no 
special orders are given to the contrary. In connection 
with it is also given the pounds of coal required per hour 



AREAS OF LAP WELDED TUBES. 



247 



for the different rates of combustiou given. The sizes of 
grates as given in the table may, in general, be reduced 
without loss of efficiency. See page 203. 

The ordinary rate of combustion for bituminous coal 
will vary from twelve to sixteen pounds per hour, per 
square foot of grate surface. The two last columns in the 
table should not be used in advance of construction, unless 
the chimney draft is known .to be sufficient to burn that 
quantity, or unless a force draft is to be employed. 

In order to facilitate any needed calculations, in which 
it would be necessary to know the relation of tube to grate 
area, the following table (LXIX) is supplied, in which the 
area is given in square feet. Tubes are always sold by out- 
side diameter. The internal areas corresponding to these 
diameters are as follows : 

TABLE LXIX. 

INTERNAL AREAS OF LAP WELDED TUBES. 



DIAM- 
ETER. 


THICKNESS. 


INTERNAL 
AREA. 


DIAM- 
ETER. 


THICKNESS. 


INTERNAL 
AREA. 


INCHES. 


INCHES. 


SQ. INCHES. 


INCHES. 


INCHES. 


SQUARE INCHES. 


3 


0.109 


6.083 


4 


0.130 


10.992 


3M 


0.119 


7.125 


4>^ 


0.130 


14.126 


3^ 


0.119 


8.357 


5 


0.140 


17.497 


3% 


0.119 


9.687 









It will be understood that this table is to be used in 
connection with and is to be regarded as supplementary 
to table LXVI. This will be found quite useful in the 
re-arranging of grate surface. 



248 



A TREATISE ON STEAM BOILERS. 



\ 



TABLE LXX. 

SHOWING THE INTERNAL AREAS OF TUBES FOR THE DIAMETERS AS 
GIVEN BELOW, AND FOR THE NUMBER OF TUBES GIVEN IN TABLE 
LXVI, ON PAGE 240. THE AREAS ARE GIVEN IN SQUARE FEET. 



DIAME- 
TER 






DIAMETERS OF TUBES. 






















BOILER 


3 


3i 


^ 


3f 


4 


41 


5 


36 


1.10 


1.14 


1.10 


1.35 


1.22 


1.18 


1.22 


38 


1.35 


1.14 


1.22 


1.35 


1.37 


1.18 


1.70 


40 


1.44 


1.68 


145 


1.55 


1.53 


1.37 


1.70 


42 


1.90 


1.88 


1.86 


1.75 


1.91 


1.96 


2.19 


44 


2.03 


1.78 


186 


2.02 


1.91 


1.96 


1.94 


46 


1.77 


1.88 


1.97 


1.88 


1.76 


2 06 


1.94 


48 


. 2.J1 


1.88 


2.09 


2.02 


1.98 


2.06 


2.19 


50 


2.32 , 


2.08 


2 21 


2 29 


2.29 


2.26 


2.43 


52 


2.41 . 


2.47 


2.79 


2.56 


2.44 


2.55 


2.55 


54 


2.79 


2.72 


2.79 


2.56 


2.75 


2.75 


2.55 


56 


3.04 


2.82 


3.19 


3.23 


3.13 


3.14 


2.79 


58 


3.13 


3.27 


3.19 


3.23 


3.44 


3.14 


3.40 


60 


3.38 


3.36 


3.60 


3.70 


3.51 


3.53 


3.65 



Should it be found necessary to re-arrange the grate 
surface from that given in the preceding tables, it is recom- 
mended that the lengths of grates be kept the same and 
diminished in width, rather than shortened. The next table 
shows the relation of tube to grate area. The increase 
shown in the line opposite forty-six inches diameter of 
boiler is due to the less number of tubes in the boilers, 
brought about by the insertion of an 8X12 man hole instead 
of a 6X8 hand hole, which was used in the smaller boilers. 
This table is to be regarded as supplementary to tables 
LXYIII and LXX. 



RELATION OF GRATE TO TUBE AREA. 



249 



TABLE LXXI. 

SHOWING THE RELATION OF GRATE AREA, AS GIVEN IN TABLE LXVIII, 
TO THE TUBE AREA AS GIVEN IN TABLE LXX. THIS TABLE 
EXPRESSES THE RATIO IN FRACTIONS OF THE GRATE SURFACE. THE 
VALUES WERE OBTAINED BY DIVIDING THE GRATE BY THE TUBE 
AREA. 



DIAME- 
TER 


DIAMETER OF TUBES. 


OF 
BOILER 


3 


13.2 


H 


3f 


4 


4^ 


5 


36 


13.6 


13.6 


11.1 


12.3 


12.7 


12.3 


38 


11.6 


13.8 


12.8 


11.5 


11.5 


13.3 


9.2 


40 


11.3 


9.7 


11.2 


10.5 


10.7 


11.9 


9.6 


42 


9.7 


9.8 


9.9 


10.5 


9.6 


9.4 


8.4 


44 


9.4 


10.7 


10.3 


9.5 


10.0 


9.7 


9.8 


46 


18.6 


10.6 


10.1 


10.6 


11.3 


9.7 


10.3 


48 


9.8 


11.0 


9.9 


102 


10.4 


10.0 


9.4 


50 


10.6 


11.8 


11.1 


10.7 


10.7 


10.9 


10.1 


52 


10.5 


10.3 


9.1 


9.9 


10.4 


10.0 


10.0 


54 


9.4 


9.7 


9.4 


10.3 


9.6 


9.6 


10.3 


56 


10.7 


11.5 


10.2 


10.1 


10.4 


10.4 


11.6 


58 


10.7 


10.2 


10.5 


10.4 


9.7 


10.7 


9.9 


60 


10.2 


10.3 


9.6 


9.3 


9.8 


9.8 


9.5 



There are more tabular boilers fitted with three-inch 
tubes than perhaps any other size, but in some sections of 
the country three and a half and four-inch tubes are more 
common. The next two tables give the same particulars 
as those given in the three-inch tables. The shells, heads, 
man holes, etc., are in no respect different from those con- 
tained in table LXYII. Boilers having diameters from 
thirty-six to forty inches inclusive are not given, as three 
and a half inch tubes are not often put in boilers of such 
small sizes. 



250 



A TREATISE ON STEAM BOILERS. 



TABLE LXXII. 

SHOWING PROPORTIONS, HEATING SURFACE, WEIGHT AND HORSE POWER 
OF TUBULAR BOILERS FITTED WITH 3>^ INCH TUBES. 



SHELL. 


NUMBER 

OF. 
TUBES. 


HEATING 

SURFACE, 

f SHELL 

AND 

WHOLE QF 

TUBES. 




WEIGHT. 




HORSE 


DIAME- 
TER. 


LENCxTH. 


SHELL. 


TUBES. 


TOTAL. 


POWER 

AT 

15 FEET, 


INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




42 


12 


32 


440 


2,242 


1,640 


3,882 


29 3 




14 


32 


514 


2,506 


1,914 


4,420 


34.3 




16 


32 


586 


2,770 


2,187 


4,957 


39.1 




.18 


32 


660 


3,034 


2,460 


5,494 


44.0 




20 


32 


733 


3.298 


2,734 


6,032 . 


48.9 


44 


12 


32 


444 


2,341 


1,640 


3,981 


29.6 




14 


32 


519 


2,617 


1,914 


4,531 


34.6 




16 


,32 


"592 


2,893 


2,187 


5,080 


39 5 




18 


32 


666 


3,169 


2,460 


5,629 


44.4 




20 


32 


740 


3,445 


2,734 


6,179 


49.3 


46 


12 


34 


470 


2,465 


1,743 


4,208 


31.S 




14 


34 


548 


2,756 


2,034 


4,790 


37.2 




16 


34 


626 


8,047 


2,324 


5,371 


41.7 




18 


34 


706 


3,338 


, 2,615 


5,953 


47.1 




20 


34 


784 


3,629 


2,905 


6,534 


52.3 


48 


12 


36 


497 


2,569 


1,846 


4,415 


33.1 




14 


36 


579 


2,871 


2,153 


5,024 


38.6 




16 


36 


662 


3,173 


2,461 ■ 


5,634 


44.1 




18 


36 


745 


3,476 


2,768 


6,244 


49.7 




20 


36 


828 


3,778 


3,076 


6,854 


55.2 


50 


12 


38 


523 


3,410 


1,948 


5,358 


34.9 




14 


38 


609 


3,811 


2,273 


6,084 


40.6 




16 


38 


697 


4,212 


2,597 


6,809 


46.5 




18 


38 


784 


4,613 


, 2,922 


7,535 


52.3 




20 


36 


871 


5,014 


3,247 


8,261 


58.1 



THREE AND A HALF-INCH TUBULAR BOILERS. 



251 



TABLE LXXII— Continued. 



SHELL. 




HEATING 




WEIGHT. 












SURFACE, 








HORSE 






NUMBER 


2 








■r> /^ ITT 17 T> 








-g- SHELL 








POWER 






OF 


AND 








AT 


DIAME- 




TUBES. 










15 FEET. 




LENGTH. 




WHOLE OF 


SHELL. 


TUBES. 


TOTAL. 


TER. 






















TUBES. 










INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




52 


12 


48 


637 


3,752 


2,461 


6,213 


42.5 




14 


48 


743 


3.988 


2,871 


•6,859 


49.5 




16 


48 


849 


4,404 


3,281 


7,685 


56.6 




18 


48 


955 


4,820 


3,691 


8,511 


63.7 




20 


48 


1,062 


5,236 


4,101 


9,337 


70.8 


54 


12 


48 


640 


3,844 


2,461 


■ 6,305 


42.7 




14 


48 


747 


4,276 


2,871 


7,147 


49.8 




16 


48 


855 


4,708 


3,281 


7,989 


57.0 




18 


48 


• 962 


5,140 


3,691 


8,831 


64.1 




20 


48 


1,068 


5,573 


4,101 


9,674 


71.2 


56 


12 


55 


722 


4,017 


2,820 


6.837 


48.1 




14 


55 


843 


4,464 


3,289 


7,753 • 


56.2 




16 


55 


962 


4,911 


3,759 


8,670 


64.1 




18 


55 


1,083 


5,358 


4,229 


9,587 


72.2 




20 


55 


1,203 


5,805 


"4,699 


10,504 


80.2 


58 


12 


55 


726 


4,300 


2,820 


7,120 


48.4 




14 


55 


848 


4,762 


3,289 


8,051 


56.5 




16 


55 


968 


5,224 


3,759 


9,183 


64.5 




18 


55 


1,089 


5,686 


4,229 


9,915 


72.6 




20 


55 


1,210 


6,148 


4,699 


10,847 


80.7 


60 


12 


62 


786 


4,601 


3,178 


7,779 


• 52.4 




14 


62 


917 


5,077 


3,708 


8,785 


61.1 




16 


62 


1,048 


5,553 


4,238 


9,791 


69.9 




18 


62 


1,178 


6,029 


4,768 


10,797 


78.5 




20 


62 


1,309 


6,505 


5,297 


11,802 


87.3 



252 



A TREATISE ON STEAM BOILERS. 



It is not a common thing to see tubular boilers fitted 
with four-inch tubes. There are some sections of the coun- 
try, however, where they are much in favor. Most of them 
are made of large diameters — that is, in the neighborhood 
of ^ve feet. Those who have used them speak of them in 
the highest terms. No doubt much of their popularity is 
due to the verv eflacient circulation of water in the boiler, 
thereby preventing priming, and all the annoyance and 
trouble incident to it. 

TABLE LXXIII. 

SHOWING PROPORTIONS, HEATING SURFACE, WEIGHT AND HORSE POWER 
OF TUBULAR BOILERS FITTED WITH FOUR-INCH TUBES. 



SHELL. 




HEATING 




WEIGHT. 










NUMBER 

OF 
TUBES. 


SURFACE, 

f SHELL 

AND 

WHOLE OF 

TUBES. 








HORSE 
POWER 

AT 
15 FEET. 


DIAME- 
TER. 


LENGTH. 


SHELL. 


TUBES. 


TOTAL. 


INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




48 


12 


26 


428 


2,569 


1,660 


4,229 


28.5 




14 


26 


498 


2,871 


1,937 


4,808 


33.2 




16 


26 


570 


3,173 


2,213 


5,386 


38.0 




18 


26 


641 


3,476 


2.490 


5,966 


42.7 




20 


26 


713 


3,778 


2,766 


6,544 


47.5 


50 


12 


30 


482 


3,410 


1.915 


5 325 


32.1 




14 


30 


562 


3,811 


2,234 


6,045 


37.5 




16 


30 


643 


4,212 


2,553 


6,765 


42.9 




18 


30 


722 


4 613 


2,873 


7,486 


48.1 




20 


30 


803 


5,014 


3,192 


8,206 


53.5 


52 


12 


32 


511 


3,752 


2,043 


5,795 


34.1 




14 


32 


596 


3,988 


2 383 


6,371 


39.7 




16 


32 


681 


4,404 


2,734 


7,138 


45.4 




18 


32 


766 


4,820 


3,064 


7,884 


51.1 




20 


32 


852 


5,236 


3,405 


8,641 


56.8 



FOUE-INCH TUBULAR BOILERS. 



25a 



TABLE LXXIII— Continued. 



SHELL. 


NUMBER 

OF 
TUBES. 


HEATING 

SURFACE, 

f SHELL 

AND 

WHOLE OF 

TUBES. 


WEIGHT. 


HORSE 
POWER 

AT 
15 FEET. 


DIAME- 
TER. 


LENGTH. 


SHELL. 


TUBES. 


TOTAL. 


INCHES 


FEET. 




SQ. FEET. 


POUNDS. 


POUNDS. 


POUNDS. 




54 


12 


36 


565 


. 3,844 


2,298 


6,142 


37.7 




14 


36 


660 


4,276 


2,681 


6,957 


44.0 




16 


36 


754 


4,708 


3,064 


7,772 


50.3 




18 


36 


849 


5,140 


3.447 


8,587 


56.6 




20 


36 


942 


5,573 


3,830 


9,403 


62.8 


56 


12 


41 


632 


4,017 


2,617 


6,634 


42.1 




14 


41 


738 


4,464 


3,054 


7,518 


49.2 




16 


41 


843 


4,911 


3,490 


8,401 


56.2 




18 


41 


949 


5,358 


3,92,6 


9,284 


63.3 




20 


41 


1,054 


5,805 


4,362 


10,167 


70.3 


58 


12 


45 


686 


4,300 


2,873 


7,173 


45.7 




14 


45 


802 


4,762 


3,352 


8,114 


53.5 




16 


45 


916 


5,224 


3,830 


9,054 


61.1 




18 


45 


1,030 


5.686 


4.309 


9,995 


68.7 




20 


45 


1,144 


6 148 


4,788 . 


10,936 


76.3 


60 


12 


46 


704 


4,601 


2,936 


7,537 


46.9 




14 


46 


821 


5,077 


3,426 


8,503 


54.7 




16 


46 


939 


5 553 


3,916 


9,469 


62.6 




18 


46 


1,055 


6,029 


4,405 


10,434 


70.3 




20 


46 


1,172 


6,505 


4,894 


11,399 


78.1 



The following evaporative test of a tubular boiler, in a 
flouring mill at Bellevue, Ohio, is by Mr. Holmes. The 
dimensions of the boiler are as follows : 

Diameter of boiler 60 inches. 

Length of boiler 15 feet. 

Number of four-inch tubes 51 

Grate surface 26 square feet. 



254 A TREATISE ON STKAM BOILERS. 

The coal used is an Ohio variety, known as Massillon 
lump. The duration of trial was ten hours. 

OBSERVATIONS. 

Total amount water weighed to boiler ...28,700 lbs. 

Total amount coal weighed to furnace 4,050 lbs. 

Total amount ash and clinker weighed dry 220 lbs. 

Total amount combustible 3,830 lbs. 

Average temperature feed water in tank 99° 

Average temperature gases in uptake 479° 

Average temperature air in fire room 93° 

Average pressure steam in boiler 72 lbs. 

Average percentage water in steam None. 

PERFORMANCE. 

Coal per hour 405 lbs. 

Combustible per hour 383 lbs. 

Water per hour 2,870 lbs. 

RESULTS. 

Pounds of water evaporated at 72 lbs. pressure 

and temperature of 99° per pound of coal 7 08 lbs. 

Equivalent evaporation from pressure of atmos- 
phere and temperature of 212° per pound of 
coal 8.15 lbs. 

Equivalent evaporation from pressure of atmos- 
phere and tempeiature of 212° per pound of 
combustible 8.61 lbs. 

This boiler was afterwards reset, and an equivalent 
evaporation at atmospheric pressure from and at 212° was 
obtained of 11.7 pounds of water, per pound of net com- 
bustible, or a gain of over 36 per cent. 

A compound tubular steam boiler, built by Mr. E. H. Ash- 
croft, Boston, Mass., is shown in figure — . The engraving 
was made from a photograph of a boiler having the follow- 
ing dimensions : 



COMPOUND TUBULAR STEAM BOILER. 



255 




256 A TREATISE ON STEAM BOILERS. 

Length of boiler 12 feet. 

Diameter 54 inches. 

118 tubes, each 3 inches diameter 12 feet long. 

Diameter of steam dome 32 inches. 

Length of steam dome 12 feet. 

Heating surface.. 1,281 square feet. 

Horse power 85 

This boiler is being well received, and results show it 
to be economical in fuel. Tests show an equivalent evap- 
oration from and at 212° of over ten pounds of water per 
pound of coal. The writer expected to be able to give a 
detailed account of the tests made to determine the capa- 
city and economy of this boiler, but they were not received 
at the time of making up this form for the press. 



CHAPTER XL 



INTERNALLY FIRED BOILERS. 

The Cornish Boiler — The Lancashire Boiler — The Fairbairn Boiler — 
The Galloway Boiler — Vertical Flue Boilers — The Shapley Boiler — 
The Baxter Boiler — Vertical Tubular Boilers — Snyder's Vertical 
Boiler — Flynn's Vertical Boiler — Suiter's Boiler — Portable Boilers 
— Semi-Portable Boilers — Locomotive Boilers. 

The internally fired boilers, in common use in this coun- 
try, are either vertical flue or tubular boilers, or of the 
locomotive type. In Europe, horizontal boilers, fitted with 
internal flues, are very common and of a type rarely seen 
in this country. In England, the internally fired boilers 
are usually of the Cornish or the Lancashire varieties ; 
there has been a growing dislike to externally fired boilers 
in that country for many years, during which time the 
above named boilers have been growing in favor, and are 
now so thoroughly intrenched behind public opinion, that 
it would require a remarkably good showing in economy 
and durability in a rival to gain similar popularity. 

The Cornish boiler owes its name to the circumstance 
of its having been first introduced in Cornwall, England. 
The original inhabitants of Cornwall were Celts, speaking 
the Cornish language, which, though now extinct, or no 
longer spoken by the people, the name of Cornish still 
lives, and is applied to many technical names — for example, 
Cornish mining, Cornish agriculture, etc. ; hence, Cornish 
boilers, meaning thereby a particular kind of boiler orig- 
inally in or peculiar to Cornwall. 
(18) 



258 



A TREATISE ON STEAM BOILERS. 



This boiler was introduced early in the present centuryj 
by Richard Trevithick, an English engineer, born in Corni 
wall, and one whose name is inseparably connected with' 
the modern steam engine. 

This boiler consists of a horizontal cylindric shell, with 
flat ends and fitted wdth one large flue passing through 
from front to back of the boiler and securely fastened to ■ 
the two ends by riveted joints. This large flue contains 
the grate on which the fuel is burned, the products of com- 
bustion passing through the flue to the back end of the 
boiler, returning, by a suitable arrangement of the brick 
work along the sides of the boiler to near the front end, 
thence downward and along the bottom of the boiler to 
the rear end, and from thence to the chimney. This ar- 
rangement of exterior flues is shown in figure 62. 

A Cornish boiler is to be distinguished from a single 
flue boiler in its having the furnace arranged in the flue, 
and thus being an internally fired boiler. 

The usual course of heated gases in any arrangement 

of boiler and furnace is from 
below upwards. It was first shown 
by Peclet and is now generally 
recognized, that a great advantage 
in point of thorough convection of 
heat and consequently in economy 
of fuel, is gained by causing the 
course of the hot gas to be on 
the whole from above downioards ; 
because then, the hottest strata of 
the furnace gas, being uppermost, 
spread themselves out above the denser and colder 
strata which are below, and so diff'use themselves more 
uniformly throughout all the passages than they do when 
made to ascend from below.* 




Figure 62. 



"• Rankine. 



CORNISH BOILERS. 259 



It would naturally be inferred from an inspection of the 
engraving that the heating surface is of the best possible 
arrangement to insure economy of fuel. The feed water 
enters the boiler near the bottom, where the water is cool- 
est ; as it rises becomes more highly heated until the sur- 
face is reached, where the steam is given off. There is 
ample facility for circulation, and the conditions are favor- 
able to rapid evaporation. The large water surface lessens 
the tendency to priming and thus practically insures dry 
steam. 

Under the most favorable conditions, as regards con- 
struction, fuel used and rate of combustion, about eight 
pounds of water may be evaporated per pound of coal. 
In this respect the Cornish boiler is about on an equality 
with our ordinary cylinder boiler. The rate of combus- 
tion in Cornish boilers is not far from ten pounds of coal 
per square foot of grate, in good ordinary firing, and from 
this down to ^ve or six pounds in slow firing. 

These boilers must, of necessity, be of large diameter 
when required to be of any considerable power. This also 
necessitates a large flue, in order to afford the necessary 
grate area and heating surface. Increasing the diameter 
of the fine decreases its power to resist collapse, whieh 
may occur either by overpressure or overheating. These 
flues are often strengthened by means of heavy wrought 
iron rings, which are secured to the ends w^liere the sec- 
tions are to be joined to form a continuous flue. Figure 
63 represents such a joint. This ring 
of angle iron gives the flue great stiff- 
ness, and increases its power to resist 

collapse by shortening the length of the figure es. 

span between supports. A much better device is that of 
Mr. Adamson, shown in figure 64. The flue is made in 
sections, with welded seams and flanged ends, which are 





260 A TREATISE ON STEAM BOILERS. 

secured end to end by riveted joints, as shown, render- 
ing collapse almost impossible; it is, 
also, a very superior expansion joint, 
thus preventing the shell being 
strained, as is often the case with 
plain flues, and presents a further 

Figure 64. • i i i i 

advantage m that both the rivets 
and edges of the plates are kept entirely free from the 
action of the fire. 

When a fire is started in any internally fired boiler, 
having a large flue, such as the Cornish or Lancashire, the 
flue will be heated first, and will expand in length a con- 
siderable distance before the external plates, or the shell 
of the boiler, has received any considerable degree of heat. 
Unless some provision is made for this unequal expansion, 
it is likely to lead to a great deal of annoyance by leaky 
joints, if not to something more serious in the way of rup- 
ture. 

The following table gives the principal dimensions of 
Cornish boilers, as taken from the catalogue of Abbott & 
Co., IN'ewark-upon-Trent, England: 

The Lancashire boiler is an internally fired boiler, and 
differs from the Cornish in having two flues and furnaces 
instead of one. It was introduced, in 1844, by Fairbairn 
and Hetherington in Manchester, and is, therefore, called 
a Lancashire boiler. The insertion of two smaller flues in 
the shell of a boiler, instead of one large one, was to 
strengthen the boiler against collapse. This is, perhaps, 
the most popular for large boilers of any in England to-day. 
Figure 65 represents a longitudinal section, and figure 66 
a cross section, of a Lancashire boiler. 



CORNISH BOILERS. 



261 



TABLE LXXIV. 

SHOWING THE PRINCIPAL DIMENSIONS OF "NEWARK" STANDARD SIZE 

CORNISH BOILERS. 







SHELL. 




HORSE 










POWKR. 




1 








DIAME- 
TER. 


LENGTH 




FT. 


IN. 


FT. 


IN. 


2 


2 


9 


6 





4 


3 


9 


7 


6 


6 


4 


3 


10 





8 


4 


4 


13 





lO 


4 


6 


14 





12 


4 


8 


15 





14 


4 


9 


16 





16 


4 


9 


17 


6 


" 18 


5 





18 






DIAME- 


TER 


OF 


FLUE.- 


FT. 


IN. 


1 


3 


2 





2 


2 


2 


2 


2 


2 


2 


4 


2 


4 


2 


6 


2 


9 



DOME. 



DIAME- 
TER. 



FT. IN, 

1 

1 3 

1 6 

1 6 

1 9 

1 9 

1 9 

1 9 

2 



FT. IN. 

1 

1 6 

1 9 

1 9 

2 
2 
2 
2 6 
2 6 



THICKNESS AND QU 


iLITY 




OF PLATES. 




APPROX- 
























WEIGHT 


SHELL 


ENDS. 


FLUE. 


DOME. 




INCH. 


INCH. 


INCH. 


INCH. 


POUNDS 


5 T? 
16^ ^ 


% 


BB 


% B 


5 


BB 


1,900 


% B 


3^ 


BB 


% B 


% 


BB 


3,248 


■% B 


>^ 


BB 


Ys B 


% 


BB 


4,480 


%B 


^ 


BB 


Ys B 


% 


BB 


5,824 


%B 


y^ 


BB 


% B 


% 


BB 


6,720 


% B 


K 


BB 


% B 


% 


BB 


7,280 


% B 


% 


BB 


% B 


% 


BB 


7,840 


% B 


^ 


BB 


% B 


% 


BB 


8,512 


% B 


3^ 


BB 


T^ B 


% 


BB 


10,080 



For properties of B and BB iron i)lates, see pages S3-4. 




Figure 65. 



These engravings represent the arrangement and set- 
ting of the boiler at the trials at Mulhouse, and do not 
contain the welded and flanged flues, as shown in detail at 

-In every case, Low Moor, or equal quality plates, are put over the fire in the flues. 
—Abbott & Co. 



262 



A TREATISE ON STEAM BOILERS. 



figure 64. The principal dimensions of the boiler used in 
the trial are as follows : * Shell, 6 feet 6f inches diameter 

by 25 feet 9 inches long; two flues, 
each 2 'feet S^-q inches diameter. 
The shell plates were 0.63 inch 
thick, the end plates 0.748 inch 
thick, and the flue plates 0.51 inch. 
The combined width of the fire 
grates is 4 feet 6f inches, and their 
length 5 feet 1 inch ; this length 
includes 6-^ inches formed by the 



^^^» parts of the bars resting on iron 




Figure 66. 



supports. Taking the effective 
length of the grates, therefore, at 4 feet 6^ inches, we 
get a fire grate area of 20.5 square feet. 



TABLE LXXV. 

GIVING AN ABSTRACT OF RESULTS OBTAINED IN EVAPORATIVE TESTS 

WITH THE LANCASHIRE AND FAIRBAIRN BOILERS, AND USING 

SAARBRUCK COAL.f [MULHOUSE EXPERIMENTS]. 



Coal consumed per day of eleven hours 

Net fuel consumed per day of eleven hours 

Water evaporated per day of eleven hours 

Equivalent evaporation from and at 212° 

Actual evaporation per pound of coal 

Actual evaporation per pound of net fuel 

Equivalent evaporation from and at 212° per pound of coal 

Equivalent evaporation from and at 212° per pound of net fuel- 
Equivalent evaporation from and at 212° per square foot of 
heating surface per hour 



Mean temperature of escaping gases 

Weight of air supplied per pound of coal burnt., 



LANCASHIRE 
BOILER. 



3,628 lbs. 

3,261 lbs. 

24,178 lbs. 

28,247 lbs. 

6.66 lbs. 

7.41 lbs. 

7.79 lbs. 

8.66 lbs. 

4.19 lbs. 

555° 

13.99 lbs. 



FAIRBAIRN 
BOILER. 



3,648 lbs. 

3,263 lbs. 

25,852 lb 

30,187 lbs. 

7.09 lbs. 

7.92 lbs. 

8.27 lbs. 

9.25 lbs. 

2.70 lbs. 

322° 

14.98 lbs. 



* Engineering. 

t For analysis and calorific value of Saarbruck coal, see Combustion of Coal, page 187. 



LANCASHIRE BOILERS. 



263 



The total heating surface of the boilers is 612.5 square 
feet, divided as follows : 

SQUARE FEET. 

Surface of outer shell exposed in side and bottom 

flues 271.03 

Surface of internal flues, deducting parts below the 

grates , 333.25 

Surface at back end of boiler 8.22 

Total 612.50. 

The next table gives the sizes of Lancashire boilers, as 
taken from the catalogue of Abbott & Co,, for the first 
three boilers in the table; the two following are from 
Tangje Brothers & Holman, London, England : 

TABLE LXXVI. 

LANCASHIKE BOILERS. 







SHELL. 




DIAME- 
TER 
OF 
FLUE.* 




DOME. 




THICKNESS AND QUALITY 
OF PLATES. 


APPROX- 


HORSE 




















IMATE 


POWER. 




. 






















WEIGHT. 




DIAM. 


LENGTH 


DIAM. 


HEIGHT 


SHFLL 


ENDS. 


FLUE. 


DOME. 






FT. 


IN. 


ft: 


IN. 


FT. IN. 


FT. 


IN. 


FT. 


IN 


INCH. 


INCH. 


INCH. 


INCH. 


POUNDS. 


20 


5 


9 


19 





2 


2 


3 


2 


6 


l^B 


^ BB 


Ys B 


% BB 


13,440 


25 


5 


6 


25 





2 


2 


3 


2 


6 


l^B 


y^ BB 


%B 


% BB 


17,024 


30 


6 





26 





2 .4 


2 


6 


3 





^B 


y^ BB 


%B 


T^BB 


20,720 


35 


fi 


q 


R1 





2 ly^ 

2 9 


R 





4 


1 










32,480 
36,400 


40 


7 





34 





3 


1 


4 


3 





















The following test of a Lancashire boiler shows the 
evaporative power, rate of combustion, and much other 
data of interest : 

Boiler trials at the South Metropolitan Gas Works, Lon- 
don, England, December 19-21 and January 2-4, 1877-8 : 



264 A TKEATISE ON STEAM BOILERS. 

Diameter of boiler 6 feet 6 inches. 

Length of boiler 25 feet Cinches. 

Diameter of each furnace (2) 2 feet 3 inches. 

Grrate surface (whole) 27.75 square feet. 

Grate surface (as bricked up) : 16 square feet. 

Total heating surface 679 square feet. 

Heating surface, deducting lower half of 

furnaces 504 square feet. 

Proportion of air space through bars to 

total grate surface 0.2 to 1. 

This boiler was set in the usual manner. The products 
of combustion, after passing to the end of the boiler, 
returned to near the front end, thence downward to the 
lower flue and along the bottom to the rear end of the 
boiler, and thence to the chimney. 

The furnaces were fitted with rocking bars, the bars 
being zigzag instead of straight. The rocking arrange- 
ment could not be 'used on the days in which the grates 
were bricked up. 



EVAPORATIVE TESTS. ( 

GRATE. 



WHOLE. PARTIAL. 

Duration of trial, hours 8.50 11.75 

Temperature of feed water , 50.3° 49.1° 

WATER FED INTO THE BOILER. 

Per hour, in pounds 1,228 1,288 

Per square foot of total heating surface, 

pounds 1.81 1.89 

Per pound of coal, pounds (total) 6.88 9.98 

Equivalent evaporation from and at 212° 

pounds 8.0 11.4 

Equivalent evaporation from and at 212°, 

per pound of combustible 8.5 11.7 

FUEL USED. 

Cefn (South Welsh) coal in both tests ; 
percentage of non-combustible and 
of water in the fuel 6.0 3.0 

Total fuel per hour, pounds 178.7 129.0 

Total fuel per square foot of grate sur- 
face, pounds 6.4 8.1 



THK FAIRBAFRN EOILER. 



265 



GRATK. 
WHOLK. PARTIAIi. 



Total fuel per indicated horse power, 

pounds 3.64 

--, T^. „ ^ THeavy and black, 

Condition ot fire -{ about 8 inches 

(, thick. 

Cost of evaporating one gallon of water, 

cents 0.31 

Factor of evaporation 1.16 

Rate of transmission of heat (thermal 
units per square foot of total heat- 
ing surface per minute), in heat 

units. 33.7 

Steam pressure in boiler, above atmos- 
phere, pounds 52 5 

Indicated horsepower 49.1 

Barometer 29.91 

Temperature of the air in boiler house.. 47.0° 

Grate surface, square feet 27.75 

Total heating surface, square feet 679 



2.79 

Lifi^ht and brig:ht,. 
about 5 inches 
thick. 



0.21 

1.14 



34.7 

55.9 
46.2 
30.37 
44.5° 
16.0 
679 



The Fairhairn boiler, shown in figures 67 and 68, is a 
modification of the Lancashire boiler, and might be said to 




^^»^^^^^^'.M^fc^.#/M^^M^:^S;M€?//f^/^e^^ 



Figure 67. 



be an internally fired elephant boiler. It consists of three 
cylindric shells, two of these — each traversed concentrically 
by an internal flue — being placed side by side at a short 



266 



A TREATISE ON STEAM BOILERS. 




FlGUKK 68. 



distance apart, while the third is placed above and between 
them, being joined to them by suitable connecting tubes. 

The boiler shown in the above 
engraving is a representation 
of the one used in the experi- 
ments at Mulhouse, and while 
possessing all the salient points 
of the Fairbairn boiler, is 
slightly modified in design, the 
two flues in the lower shells 
being placed eccentrically as 
shown. * These two lower 
shells are each 4 feet 1^ inch 
diameter by 25 feet 9 inches 
long, and the flues they contain are 2 feet 3^^ inches diam- 
eter. The lower cylinders are each connected by three 
tubes or mouth pieces with the upper cylinder, which is 3 
feet 8^ inches in diameter by 22 feet llf inc?ies long. 
The upper cylinder is made of plates J inch, and the two 
lower of plates 0.53 inch thick, while the internal flues are 
made of 0.51 inch and the ends of 0.71 inch plates. 

The grates, which are contained in the internal flues 
of the lower cylinder, are precisely identical with those of 
the Lancashire boiler already described. This boiler being 
one of the three experimented with by the Societe Alsaci- 
enne de Constructions Mechaniques, Mulhouse. These were 
the French or Elephant boiler, described on page 223, the 
Lancashire boiler, described in this chapter, and the Fair- 
bairn boiler. The heating surface of the latter is 1017.48 
square feet, divided as follows : 

* Engineering. 



THE GALLOWAY BOILER. 267 

SQUARE FEET. 

Surface exposed by the upper cylinder 144.88 

Surface exposed by the two lower cylinders to the 

second "run" of gases 314.49 

Surface exposed by the two lower cylinders to the 

third "run" of the gases 182.96 

Surface exposed by six connecting tubes 34.04 

Surface exposed by two internal flues, deducting 

surface below grates 333.27 

Surface exposed at front of upper cylinder 3.84 

Total 1.017.48 

It will be seen, on reference to the engraving of tliis 
boiler, that the setting is so arranged that, on leaving the 
internal flues of the lower shells, the gases return to the front 
end along the sides and bottoms of the two lower cylinders, 
and thence pass to the chimney between these cylinders 
and the third one above, a mid-feather wall dividing the 
flues so that the products of combustion from the two 
furnaces do not unite until just before entering the chimney. 

An abstract of results obtained in the tests at Mul- 
house may be found in table LXXV, in comparison with 
that of the Lancashire boiler. 

The Galloway boiler, shown in figure 69, is a modification 
of the Lancashire boiler, in which 
the two furnaces at the front end 
unite in one back flue of an irreg- 
ular oval form. This flue consti- 
tutes the chief feature in the "Gal- 
loway boiler," in which are placed 
conical water tubes, fixed in an up- 
right position, in such a way as to 
support the flue and to intercept 
and break up the flame and heated gases, when passing 
from the fire grate or furnaces to the chimney. Along the 
sides of the flues there are also placed several wrought 




FlGUKE G9. 



268 A TREATISE ON STEAM BOILERS. 

iron stops or bafflers, which deflect the currents of heated 
air and cause them to impinge against the tubes, so as to 
absorb all the available heat possible. 

The conical water pipes, or " Galloway tubes," as they 
are now generally called, present a direct heating surface 
to the action of the flame or heated gases, and thus eft'ects 
a great saving in fael ; they also promote rapid circulation 
of water and thereby maintain that uniform temperature 
which is so essential to the durability and safety of all 
steam boilers. Unequal expansion or contraction is 
avoided and its attendant evils, undue strains and event- 
ual rupture. 

Messrs. W. & J. Galloway exhibited three of their boil- 
ers, in the British section, at the Centennial exhibition, in 
which an important improvement over their former designs 
was shown. This improvement consists in the arching ot 
the bottom part of the oval back flue, by means of which 
greater facilities arc fornished for cleaning and examining 
the lower part of the boiler when required. A further 
advantage is also obtained by having the conical tubes all 
radiating from one center, as shown in the engraving; 
they are consequently one uniform length and are inter- 
changeable. 

These boilers were each seven feet diameter by twenty- 
eight feet long. The shell was of Bessemer steel plates, 
three-eighths inch thick, with double riveted longitudinal 
seams. The two furnaces were each two feet nine and a 
half inches diameter by seven feet six inches long, made 
of steel plates, in three rings, flanged and riveted together, 
as already described on page 260. The main flue contained 
in it thirty-three conical water tubes, each ten and a half 
inches diameter at the top, or large end, and Rve and a half 
inches diameter at the lower end. These tubes are welded 
and flanged from one plate, and thus present no joints 



VERTICAL BOILERS. 269 



other than the flange joints by which they are attached to 
the flue. 

The following data shows the evaporating power of 
this boiler, as determined at the Centennial exhibition; 
one trial using anthracite, and the other trial using bitu- 
minous coal. Two regular trials were made with each 
kind of coal — one for economy, the other for capacity : 

ANTHRACITE. BITUMINOUS. 

Pressure of steam above atmosphere.. 70.06 70.12 

Temperature of steam, average 310° 310° 

Temperature of uptake, average 303° 324.6° 

Temperature of feed water, average... 56° 55° 
, Coal consumed per square foot of grate 

per hour 8.87 lbs. 7.27 lbs. 

Water evaporated per pound of coal.. 8.51 lbs. 9.18 lbs. 

Water evaporated per pound of com- 
bustible 9.58 lbs. 10.07 lbs. 

Water evaporated per hour 2,946 lbs. 2,603 lbs. 

Water evaporated per square foot of 

heating surface per hour 3.03 lbs. 2.67 lbs. 

Percentage of moisture in the steam... 0.22 0.57 

Number of pounds of saturated steam 
evaporated at 70 lbs. from 212°, 
equivalent to total heat units de- 
rived from the fuel — 

Per pound of coal 9.94 10.69 

Per pound of combustible 11.19 11.72 

Per square foot of heating 

surface 3.53 3.11 

Horse power, at 121^ square feet 77.88 77.88 

Horse power, on the basis of 30 lbs. of 
water actually evaporated per 

hour, per horse power.. 98.19 86.77 



Vertical boilers — There has been a very great demand in 
this country, within a few years past, for small internally 
fired vertical boilers. These are used for furnishing steam 



270 



A TREATISE ON STEAM BOILERS. 



for small engines, pumps, heating, etc. The simplest form 

of these boilers is shown in fig- 
ure 70. When used for heating, 
where pressures are only five to 
ten pounds, it is not usually the 
practice to put in stay bolts or 
braces; but when used for fur- 
nishing steam for small engines or 
pumps, or for any purpose where 
the pressures may be anywhere 
from fifty to seventy-five pounds, 
the stay bolts and braces should 
always be put in. Sometimes a 
ring is put in between the outer 
shell and the fire box at the bot- 
tom, and at other times the fire 
box is flanged, as shown in the 
engraving. The writer has made 
iiU them both ways, but prefers the 
Figure 70. latter. Each boiler should have 

one or naore hand holes just above the crown sheet, and 
at least three in the bottom, as shown in the engraving. 

These band holes are quite essential to inspection and 
cleaning and should never be omitted. The writer once 
saw a boiler of this description, in which the space between 
the fire box and the shell had completely filled with scale^ 
and if the boiler had been used for any purpose in which 
it would have been necessary to use even a moderate pres- 
sure, disastrous results must have certainly followed. 
Whether the blame could attach to the owner or not, it cer- 
tainly could to the boiler maker, who was guilty of little less 
than criminal negligence in not putting them in. The wri- 
ter has seen what might be called a clever trick in evading 
this known duty in boiler construction in order to save a 
few dollars — that is, by the insertion of two or three one 




VERTICAL FLUE BOILERS. 



271 



inch or one inch and a quarter pipe plugs. This is not 
sufficient, and nothing less than a 2X3 hand hole should 
ever be used, even in the smallest boilers, and as much 
larger as the circumstances will permit. 

The ring around the fire door opening should be pre- 
ferably of wrought iron, though cast iron is often used. 
If a ring is to be used at the bottom of the boiler instead of 
fianging the fire box, as shown in the engraving, it should 
be of wrought iron alioays. 

The following table gives the principal dimensions of 
vertical fiue boilers. The shell being \ inch thick 
in all cases, the fire box -^ inch thick, the outside 
heads f inch for all sizes up to 44 inches, inclusive, and -^ 
inch thick for larger diameters. The inside heads are ^ 
inch thick up to 40 inches, and f inch for the other sizes. 



TABLE LXXVII. 

PUOPORTIONS AND WEIGHTS OF VERTICAL FLUE BOILERS AS SHOWN IN 

FIGURE 70. 



SHELL. 


FIRE 


BOX. 


FLUE. 


GRATE 
AREA. 


HEATING 
SURFACE. 


HORSE 
POWER 

AT 
9 FEET. 


WEIGH T. 


DIAM. 


HEIGHT 


DIAM. 


HEIGHT 


DIAM. 


AREA. 




INCHES 


INCHES 


INCHES 


INCHES 


INCHES 


SQ. FT. 


SQ. FEET. 


SQ. FEET. 




POUNDS. 


30 


60 


25 


83 


9 


.44 


3.41 


24.0 


2.7 


1,087 


32 


06 


27 


36 


9 


.44 


3.98 


28.9 


3.2 


1,236 


3i 


72 


29 


39 


10 


.55 


4.59 


34.0 


3.8 


1,409 


36 


78 


31 


42 


11 


.66 


5.24 


39.6 


4.4 


1,585 


38 


84 


32 


45 


11 


.66 


5.59 


43.6 


4.8 


1,777 


40 


90 


34 


48 


12 


.79 


6.31 


49.9 


5.5 


2,012 


42 


96 


36 


51 


12 


.79 


7.07 


55.8 


6.2 


2,245 


44 


102 


38 


5i 


13 


.92 


7.88 


62.9 


7.0 


2,473 


46 


108 


39 


57 


14 


1.07 


8.30 


68.8 


7.6 


2,786 


48 


114 


41 


«0 


15 


1.23 


9.17 


76.6 


8.5 


3,036 



These weights do not include either the grate or hase, but do include stays and braces 



272 A TREATISE ON STEAM BOILERS. 

The diameters of the outer shell and for the fire hox, a» 
given in the above table, are inside measure. The height 
of the boiler is that from the bottom of the lower joint to 
the top of the upper head. In regard to this height, if it 
is found to be inconveniently high, it may be lowered 12 
to 18 inches for the lower half of the table without inter- 
fering with the heating surface or decreasing the boiler 
power. The height of the fire box is from the bottom of 
the boiler to the lower side of the head. The water space 
for boilers 30 to 36 inches, inclusive, is 2^ inches ; from 38 
to 44 inches it is 2^1 inches, and from 46 to 48 inches it is 
3^^ inches. The diameter of the flue is inside measure. 

In boilers of this class the fire box is the main thins^ 
as a matter of course, and ought to be large and roomy. 
If it were thought advisable, the heights given in the table 
might be reasonably extended. In the examples given 
above, the fire boxes have parallel sides ; if they were 
inclined, as shown in figure 71, it would improve the cir- 
culation, and add but very little, if anything, to the cost. 

The Shapley boiler, as made by the Knowles Steam Pump 
Works, is shown in sectional elevation in figure 71. 

This boiler is made in two sections, the lower section 
containing the greater part of fire box and the vertical 
tubes ; the latter are situated between the fire box and out- 
side shell, having their lower terminus in two base flues, 
extending from either side of ash pit entrance to smoke 
stack at the rear of the boiler. The upper section is prin- 
cipally a reservoir for steam. The fire box extends a short 
distance into the upper section, and the products of com- 
bustion are conveyed through cross tubes, to the vertical tubes 
as indicated by the arrows, thence downward to the base 
flues and so to the chimney. The tubes and crown sheet 
are removed as far from the intense heat of the fire as the 
size of the boiler will permit ; this also insures a large com- 



THE SJIAPLEY BOILEK. 



273 




bustion chamber, a thing which is alwa3^s to be secured^in 
internally fired boilers whenever possible. The tubes are 
(19) 



274 



A TREATISE ON STEAM BOILERS. 



well protected from the action of the fire, and are quite 
accessible in case they need repairs. 

The Baxter boiler — The boiler furnished with the well 
known Baxter engine, as built by the Colt's Patent Fire 
Arms Manufacturing Company, is shown in figure 72, 
which is a representation of the boilers regularly furnished 
with their engines, with the single exception of their small- 
est size, or two horse power, which is illustrated in figure 
74. Referring to figure 72, it will be seen that all the 




Zi-xrAAAiJi^ 



Figure 72. 



heating surfaces are below the water line. The combus- 
tion chamber is large, and of a form to insure economy of 
fuel. The fire box is provided with descending flues. 



THE BAXTER BOILER. 



275 




passing through the water space and communicating with 
a jacket surrounding the 
water space and extending 
up to the water line of the 
boiler, so as to leave the 
dome uncovered, and to 
which the engine is at- 
tached, as shown. Figure 
73 is a horizontal section 
showing the arrangement of 
the. descending Hues, the 
furnace . door, the grates, 
and the jacket surrounding 
the boiler containing the figure 73. 

heated products of combustion on their way to the chim- 
ney. The design of this boiler is such as to insure a pro- 
per circulation of water, hence there is little or iio danger 
of priming. 

The smallest size, or two horse power, is shown in sec- 
tional elevation in figure 74, 
and differs from the one al- 
ready described in having no 
descending flues, as shown in 
the other engravings, having 
instead an internal chamber, 
or fire box, with an annular 
heating chamber between it 
and the inside of the boiler. 



Vertical tubular boilers-;— The 
commonest form of a vertical 
tubular boiler is shown in fig- 
ure 75. It does not differ from 
the vertical fine boiler, already 




Figure 74. 



described, except in having tubes instead of fines above 



276 



A TREATISE ON STEAM BOILERS. 



the furnace. This is the form of boiler usually supplied 
with the numerous small vertical engines now offered in 
the market. When "properly made, it is an economical 
boiler, and with proper management will be found to be 
quite durable in service. 

The tubes in vertical boilers, especially if short ones 
are employed, should not be of large diameter. The diam- 
eters usually employed are two, two and a half and three 

inches. The number of tubes may 
be such that their aggregate area 
shall equal one-eighth of the 
grate area. The following table 
(LXXYIII) gives the principal 
proportions of vertical tubular 
boilers having the same size of 
hre box as given in table LXXVII, 
for vertical flue boilers. This is 
higher than vertical fire boxes are 
usually made for the diameters 
given. The writer" attaches so 
much more importance to fire 
box heating surface than to tube 
surface that he recommends high 
fire boxes rather than long tubes, 
especially as the heating surface 
proper is that only to the water 
line and not to the upper limit 
of the tubes. The height of water 
carried above the crown sheet in 
vertical boilers is scarcely ever more than twelve inches; 
the value of the tube surface may be easily over estim- 
ated by not taking into account the comparatively small 
portion of the whole surface actually utilized. 




I 



limiiiiMim. „ 




FiGUllK 



VERTICAL TUBULAR BOILERS. 



277 



TABLE LXXVIII. 

PKOPORTIONS AND WEIGHTS OF VERTICAL TUBULAR BOILERS, AS SHOWN 

IN FIGURE 75. 



SHELL. 


FIRE 


BOX. 


TUBES. 






HORSE 
















GRATE 
AREA. 


HEATING 

SUKFACE 


POWER 
AT 


WEIGHT. 
















DIAM. 


HEIGHT 


DIAM. 


HEIGHT 


NO. 


DIAM. 






12 FT." 




INCHES 


INCHES 


INCHES 


INCHES 




INCHES 


SQ. FEET. 


SQ. FEET. 




POUNDS. 


30 


60 


25 


33 


36 


2 


3.41 


61.2 


5.1 


1,163 


32 


66 


27 


36 


42 


2 


3.98 


77.7 


6.5 


1,367 


34 


72 


29 


39 


48 


2 


4.59 


95.5 


8.0 


1,583 


36 


78 


31 


42 


55 


2 


5.24 


116.7 


9.7 


1,825 


38 


84 


32 


45 


36 


2)^ 


5.59 


109.9 


9.2 


1,995 


40 


90 


34 


48 


42 


2% 


6.31 


134.5 


11.2 


2,301 


42 


96 . 


36 


51 


58 


2>^ 


7.07 


1G1.4 


13.4 


2,604 


44 


102 


38 


54 


53 


2>^ 


7.88 


187.7 


15.6 


2,941 


46 


108 


39 


57 


54 


2)^ 


8.30 


. 202.7 


16.9 


3,195 


48 


114 


41 


60 


60 


23^ 


9.17 


235.4 


19.6 


3,611 


50 


120 


43 


60 


66 


2>^ 


10.08 


277.7 


23.1 


4,000 


52 


120 


45 


60 


72 


2% 


11.04 


290.0 


24.2 


4,225 


54 


120 


46 


60 


51 


3 


11.54 


266.6 


22.2 


4,291 


56 


120 


48 


60 


55 


3 


12.57 


286.0 


23 8 


4,518 


58 


120 


50 


60 


60 


3 


13.64 


309.3 


25.8 


4,815 


60 


120 


52 


60 


66 


3 


14.75 


335.6 


28.0 


5,083 



These weights do not include the grates, base or fit- 
tings of any kind, but do include hand hole plates, stays, 
braces, etc. 

■ In horizontal tubular boilers the grate area may be 
made of any size best suited to the fuel to be used and the 
quantity to be burned. In vertical tubular boilers the 
grate area is fixed by the diameter of the fire box, and the 
fuel must be selected with reference to the most economi- 
cal consumption. Anthracite nut coal or crushed coke 

■■' If the ordinary number of tubes are put in the head, then use 15 as a divisor. 



278 A TREATISE ON STEAM BOILERS. 

will, in general, be found to give the best results when 
burned in vertical boilers than if bituminous coal is used, 
unless the latter is verj slowly burned and sparingly fired. 
It should be broken up into small pieces not larger than a 
hickory nut, or about the size of anthracite nut. 

One of the inconsistencies in rating boiler power by 
total heating surface is shown by a comparison of the 
thirty-six and thirty- eight inch boilers in the above table. 
The fire box in the latter boiler is one inch larger in diam- 
eter and three inches higher; the tube area in proportion 
to the grate is practically the same, yet the larger boiler 
rates nearly a half horse power less than the smaller one. 

In comparing the above table with almost any manu- 
facturer's published list of vertical boilers, the first noticea- 
ble thing which will attract the reader's attention will be, 
doubtless, the small number of tubes for the diameters 
given. The writer has before him three lists of this kind — 
all of them, as manufactures, are of very high standing — 
two of them American and one English. The number of 
tubes called for in the above table, for a 48 inch boiler =: 
60, 2J inches in diameter; one of the American lists for 
the same diameter has 97, 2J inch; the other 88, 2J inch 
tubes. The English list has 30, 2J inch tubes. 

There is probably no heating surface of so little value 
as the tubes in a vertical boiler ; from half to two-thirds of 
their length is in the steam space and thus performs no 
useful service in evaporating water. The value of the 
remaining half or one-third, as the case may be, is in con- 
tact with the water, but, on account of their position with 
reference to the furnace, and thus presenting no surfaces 
against which the heated gases can impinge, it is to be 
regarded as heating surface of the very lowest order. 

The most effective heating surface in boilers of this 
class is that of the fire box; and the tube area should not 
greatly exceed that necessary for draft, merely. It is bet- 



VERTICAL TUBULAR BOILERS. 



279 



terto have a large fire box and few tubes, than a small fire 
box and many tubes. In the table given above, the tube 
area is fully fifty per cent greater than that necessary for 
draft, so that, the number of tubes given in the table ought 
not to be exceeded ; deducting one-third from the tabular 
numbers will give the smallest number of tubes admissible, 
Avhich is, one-eighth of the grate area. Between these 
two limits may be considered good if not common practice. 

In England, the tube area for vertical boilers is fixed by 
the grate area ; in this country, no account is taken of 
the grate area, but as many tubes are placed in the head as 
it will contain. By the latter 
method it is easy to figure large 
powers, but it would be a gain to 
manufacturers and users alike to 
leave out the surplus tubes and 
employ a smaller divisor for the 
rating. It is efliciency and not 
extent of heating surface that is 
needed. 

The upper end of the vertical 
tubes, as shown in figure 75, are 
liable to waste away by being 
continually heated, and in time 
will often prove very troublesome. 
Much of this is due, perhaps, to 
the too rapid firing before the 
steam is on the boiler. Many 
cases of this kind have come 
within the observation of the wri- 
ter, and some very curious phe- 
nomena, in connection with the wasting of the upper end 
of the tubes, have been disclosed. To obviate any difficulty 
of this kind the tubes may be shortened and the products 
of combustion pass up into a receiving chamber, from 




Fl&LKE 76 



280 A TREATISE ON STEAM BOILERS. 

which they may then pass into the chimney, as shown in 
the sectional elevation in figure 76. Bj this arrangement 
in the design of a boiler the tubes are wholly protected 
by the water, and will outlast those, as shown in the boiler 
on page 276. The length of the tubes should be such that 
at least six inches of water should be above them in ordi- 
nary steaming. The upper chamber must have depth 
enough to be able to use an expander in setting the upper 
ends of the tubes. This upper chamber contracts the steam 
space and largely reduces the water surface. The engrav- 
ing does not show the best proportions for a boiler of this 
kind for rapid steaming; the tubes being too numerous 
and too long, the upper chamber too large in diameter in 
proportion to that of the boiler; still it conveys the idea. 
In cases where these boilers have been used for heating, 
they have given satisfaction and are well liked. 

A modification of the above design is given in figure 
77, in which it will be observed that the upper chamber is 
conical instead of parallel, as in the boiler just described. 
This design is that of the boilers furnished by the Niles 
Tool Works, Hamilton, Ohio, with their small engines, 
from two to twelve horse power. The following table is 
compiled from their practice. This is an excellent form of 
boiler and is capable of yielding good evaporative results. 




Figure 77. 



282 



A TREATISE ON STEAM BOILERS. 



TABLE LXXIX. 

PROPOriTIONS OF VERTICAL TUBULAR BOILERS, BY 
THE NILES TOOL WORKS. 





SHELL. 


TUBES. 


HORSE 










POWER. 












DIAMETER. 


HEIGHT. 


NUMBER. 


DIAMETER. 


2 


24 


52 


18 


2i 


4 


28 


62 


27 


2J 


6 


30 


66 


37 


2J 


8 


33 


71 


42 


2^ 


10 


36 


77 


55 


2J 


12 


42 


80 


69 


2* 



Each horse power in this table is based on lo square feet of lieating surface. 

■ The commonest and at the same time the worst fault of 
small vertical tubular boilers is that of priming. There is no 
doubt that much of this trouble is due to having too many 
tubes in the boiler, which may and often does have the 
effect to retard the circulation immediately over the crown 
sheet. Priming may be induced through other causes, 
such as bad feed water, sudden reductions in pressure, etc. 
"Whatever may be the cause it is a troublesome and dan- 
gerous occurrence, and one which needs to be overcome at 
any cost. The i^ew York Safety Steam Power Compa'ny 
introduce in their vertical tubular boilers a baffle plate 
through which all the tubes pass at about the water level. 
A vertical section of tfieir- boiler illustrating this detail of 
construction is shown in ffgure 78. 

A large tube hangs from the center of this plate nearly 
to the crown of the furnace and an annular space is left 
around the outside of the baffle and between it and the 
circulator sufficient for the easy escape of the steam and 



SNYDER S VERTICAL BOILER. 



28B 



water. . The effect of this arrangement is to stop the 
current of steam and 
water tending to shoot 
up between the tubes, 
and compel it to flow 
outward and escape be- 
tween the baffle and cir- 
culator, at which point 
the steam and water 
separates, most of the 
water flowing over the 
circulator, as before de- 
scribed, while the re- 
mainder of the water 
falls on the top of the 
baf3.e plate and flows 
through the tube in its 
center, thus keeping up 
a constant current over 
the center of the crown 
sheet and among the 



tubes. It will be ob- 
served ■ that the steam 
is taken off from the very center of the boiler, and as the 
steam is delivered at the outer edge of the baffle it must 
flow inward between and around the tubes on its way to the 
engine and become dried and slightly super heated. 

This improved arrangement not only secures thorough 
circulation and dry steam, but by its use the operator is 
enabled to keep as much of the fire surface wetted as he 
may wish, by simply locating the baffle at the desired point. 




\.v.Roi3Eins .sc.w.yr 
Figure 78. 



Snyder's Vertical Boiler— A novel design for small boil- 
ers is shown in figure 79. It is not an internally fired 
boiler, and does not properly belong to this chapter. *It 



i 



28i 



A TREATISE ON STEAM BOILERS. 



is manufactured by Mr. Ward B. Snyder, IS^ew York 
city, to supply a popular demand for a small and low 
priced steam motor. Figure 79 is a sectional view of the 

boiler. The letters in the cut 
indicate spaces as follows : A, 
dome top or smoke bonnet; B, 
steam space; C, water space; 
D, furnace or fire box ; E, ash 
pit. 

This boiler consists of a-j-^g-- 
inch wrought iron lap welded 
I" cylinder, with the heads fitted, 
as shown in the engraving. A 
tubular stay rod, which also acts 
as a ^ue, is secured to the two 
heads. The engraving shows 
but one tubular stay ; others 
may be added if thought neces- 
sary. For steam yacht boilers 
the makers recommend from 
five to ten of these tubes, ac- 
cording to size of main boiler, 
which serves to keep the main 
body of water steady, in case 
of the rolling of the boat. 
A number of side tubes are fitted to the shell of this 
generator, as shown in elevation in figure 80, through 
which there is a free circulation, throwing continuously a 
stream of mixed water and steam upon the surface of the 
water in main boiler, the steam ascending and the water 
descending, as indicated by the arrow points, while outside 
and around these tubes there is a free circulation of the 
heat and abundant room for the combustion of gases. 

These side tubes, instead of being fastened in by the 
use of an expander, are held by bushings threaded inside 




Figure 79. 



Snyder's vertical boiler. 



285 



and out to fit the taper threads on the outside of the small 
tubes and the holes in. the central shell B which receive 
them. The stay 2, figure 79, is fastened in the same way 
to the top and bottom heads. 
One fact is worthy of notice 
in reference to putting in boil- 
er tubes in this way, viz, that 
the tubes and stays must be 
brought to an absolute fit be- 
fore the thread of the bushings 
can be entered or started, con- 
sequently they impose no strain 
upon the boiler of themselves^ 
as is too often the case of or- 
dinary riveted stays. 

The whole of the boiler pro- 
per is secured to the upper 
plate, marked 20 in figure 79, 
and is suspended in the inner 
casing marked 8, around which 
is still another casing, marked 
7. The air supply for the fur- 
nace may be made to enter at 
the top of the boiler, at 20, and figukk so. 

pass down into the ash pit between the casings 7 and 8. 
This will supply the fire with heated air, thus adding to 
the economy of fuel and preventing loss of heat by radia- 
tion. 

The following table gives the principal dimensions of 
these boilers : 




286 



A TREATISE ON STEAM BOILERS. 



TABLE LXXX. 

SNYDER'S VEETICAL BOILERS. 



HOKSE 


CENTRAL SHELL. 


SIDE TUBES. 


HEAT- 
ING 
SUK- 

FACE. 


BOILER. 


WEIGHT 


POWER. 


DIAM. 


LENGTH 


THICK. 


NO. 


DIAM. 


LENGTH 


DIAM. 


HEIGHT 


PLETE. 




INCH. 


INCHES. 


INCHES. 




INCH. 


INCHES. 


SQ. FT. 


INCH. 


INCHES. 


POUNDS. 


1 


10 


24 


1^ 


32 


% 


16 


14 


20 


50 


380 


2 


12 


30 


5 
16 


38 


% 


24 


24 


25 


61 


700 


3 


15 


39 


T^^ 


44 


% 


27 


35 


25 


68 


^ 850 


4 


15 


39 


^ 


88 


% 


50&36 


48 


30 


70 


1,150 


5 


15 


42 


fo 


88 


% 


50 & 42 


58 


30 


73 


1,250 


6 


15 


46 


1% 


95 


% 


60&42 


69 


35 


77 


1,300 


7 


16 


50 


1% 


105 


% 


60&50 


83 


35 


81 


1,425 



Flynn's Vertical toiler — A vertical boiler, having many 
of the good features already recommended, are contained 
in the design by Mr. Daniel Flynn, Fall River, Massachu- 
setts, and shown in elevation in figures 81 and 82. Its 
chief peculiarity lies in an enlargement or belt around the 
waist or middle portion, which is enclosed with and forms 
a part of the boiler shell, and which, in combination with 
the provision for returning gases, contributes greatly to 
the efiiciency of the invention. 

Figure 81 is a side elevation, showing, on the right 
hand, the outside of the casing, and on the left, the same 
broken away, presenting a perpendicular section of the 
interior arrangements. Figure 82 is a horizontal section 
of the boiler through XY. In Figure 81, A is the grate, 
B the fire chamber, and C and C the surrounding interior 
and exterior shells. The products of combustion follow- 
ing the direction of the arrows in the engraving, arising 
from B, first pass through the fire tubes, aaaa, into the 
mixing chamber, E. From this receptacle, the gases have 
their exit through the large openings, FFF, and after 



FLYNK S VERTICAL BOILER. 



287 




Figure 81. 



288 



A 'JREATISE ON STEAM BOILER; 



having imparted a portion of their heat in the ordinary 
manner, are retained by the conical casing, P, wliich incloses 
the space, Gr. They are consequently compelled to descend 
through the fire tubes, 6, into an annular chamber, H, 
which is inclosed in a conical casing, Q. Thence the gases 
rise through the exterior circle of fire tubes, c, and pass 




Figure 82. 



into the large space, I, and finally are discharged through 
the chimney at the apex, the object of forcing them 
through this circuitous course being to gain the full ben- 
efit of every particle of heat. The particular enlargement 
above referred to consists of the space between the annu- 
lar tube sheets. Mi M^, and the outer casing, R, in which 
are the circles of tubes, b and c. 

A special point of advantage, to which attention is 
directed, is the arrangement of the water spaces. A cen- 
tral chamber, W, will be noticed, extending above the 
crown sheets as far as the mixing chamber, E. At this 



flynn's vertical boiler. 289 

point, it is reduced in size to a tube, W, which terminates 
at the bottom of the steam drum, S, its open upper end 
being surrounded by a perforated cover, V, which prevents 
a too violent upward motion of the current generated in 
the lower chamber. In connection with the other water 
spaces which lie between the systems of tubes, surrounding 
the fire chamber and occupying the interior of the surround- 
ing casings of the mixing chamber, and finally cover the 
lower portion of the steam drum; this central chamber 
adds greatly to the already large separating surface, so 
that steam may be rapidly disengaged without carrying 
up water into the steam pipes. 

For easy access to all parts of this boiler, for repairs^ 
ample provision has been made. By removing the cover- 
ing at Q the tubes, h and c, may be readily cleaned, the 
refuse falling out at H, by its own weight. The opening 
of the door at L permits entrance to the space, I, after 
which, the door, P, being displaced, access may be had to 
the chamber, Gr. Through the opening, O, the interior of 
the steam drum may be reached. At U is the steam pipe, 
its inner end, T, opening upwards in order to prevent its 
becoming obstructed through priming of the boiler. To 
the left of the illustration is the appliance for the test 
cocks and glass water gauge, which, it is claimed, prevents 
these appendages from being choked or otherwise rendered 
inoperative. Its form is plainly shown and needs no spe- 
cial explanation. 

The efficiency of this boiler has been amply tested and 
with successful results. Attention is called to the liberal 
size of the grate, which, it will be noticed, is of much 
larger area than could be aflbrded if the lower portion of 
the boiler were made on a cylindrical instead of on a con- 
ical form. As regards economy, its consumption of fuel 
is claimed not to exceed two and a half pounds of coal 
per hour per horse power. In a recent letter to the writer, 
(20) 



290 A TREATISE ON STEAM BOILERS. 

Mr. Fiynn says that he has obtained an evaporation of llj 
pounds of water per pound of Cumberland coal. 

Ample steam space is afforded, which maybe increased 
by making the steam drum of any required height. The 
outside covering forms a jacket which confines the heated 
gases around the interior steam generator, so that every 
available portion of heat contained in the escaping gases 
is utilized. 

Suiter's patent steam boiler — This boiler is of the fire box, 
fire and water tube variety, and consists of furnace, fire 
throat, combustion chamber and horizontal return tubular 
l3oiler — the whole united to operate together. About the 
filre box, throat and combustion chamber are water spaces 
similar to the water legs in ordinary fire box boilers; and 
circulating pipes are provided from the bottom of combus- 
tion chamber to the bottom of the fire box, and from the 
sides of the horizontal boiler to the side spaces in the fire 
box. A steam pipe from the steam space in the top of the 
combustion chamber to the steam space in the horizontal 
boiler is also provided. The grate bar is somewhat novel, 
and consists of the ordinary straight single bar depressed 
to form a fire basket in the center and provided with spaces 
at the ends to admit air over the fire. 

It will be observed that the combustion chamber is so 
designed that the pressure on the upper and lower sheets 
tends to tighten the joints of the vertical tubes and thus 
require no special staying, the circulating pipes acting as 
supports. 

Messrs. Slusser & Suiter, Cincinnati, Ohio, have in use 
at their works a small boiler, as shown in Figure 83; it is 
of the following dimensions: Horizontal shell four feet 
ten inches long by twenty-six inches diameter, with 
twelve three-inch tubes whole length of shell. Fire box 
twenty-six inches diameter inside by eighteen inches ver- 



SULTER S BOILER. 



291 





292 A TREATISE ON STEAM BOILERS. 

tical depth from bottom of boiler to grate, with two 
inches water space around the fire chamber and ash pit. 
Ash pit same diameter as fire box and 12-^ inches deep, 
with a water bottom two inches deep, connected with the 
water spaces around the fire chamber. The fire throat, 
which takes the place of the ordinary bridge wall, has a 
constant width of twenty-six inches and a vertical depth 
ranging from ten inches at the front end to 'G.ve inches at 
the back end; the length of throat parallel with axis of 
boiler is eighteen inches. The bottom of the throat is an 
arc of a circle of thirteen inches radius and has a two-inch 
water space connected with the water spaces of fire box 
and combustion chamber. The combustion chamber has a 
diameter inside of twenty-six inches and a vertical height 
in center of twenty-seven inches. The bottom of the com- 
bustion chamber is provided with an entrance hole for 
examinatidn of the interior and removal of soot and ashes 
as these may collect in the use of the boiler; this hole is 
surrounded by an annular water space two inches deep. 
The water space above the crown plate of combustion 
chamber and the annular space around the entrance hole 
are connected by vertical water tubes to secure circulation. 
The chimney is of sheet iron, twelve inches diameter and 
about thirty-two feet high from surface of fire grate, con- 
nected to front of horizontal section of boiler by the usual 
breeching. 

An evaporative test was made in April, 1878, underthe 
direction of Mr. John W. Hill, consulting engineer in that 
city. 

The coal fired during the trial was Pittsburg, taken 
from the pile in the boiler room ; this was weighed and 
dumped in charges of 25 pounds. The water was meas- 
ured to the boiler in charges of 300 pounds, by duplicate 
tanks connected with suction of feed pump. 



TEST OF SULTER's BOILER. 293 

Calorimeter tests of the quality of steam produced 
exhibited a slight super heat ; hence, all the water pumped 
into the boiler was evaporated. 

DIMENSIONS OF FURNACE AND BOILER. 

Length of horizontal shell 4 feet 10 inches. 

Diameter of horizontal shell 26 inches. 

Diameter of fire box inside..- 26 inches. 

Diameter of combustion chamber inside 26 inches. 

Horizontal tubes 12, 3 inches. 

Vertical tubes 6, 3 inches. 

Heating surface 100 square feet. 

Grate surface 1 .983 square feet. 

Cross section of tubes 84.82 square inches. 

Heating to grate surface 50.43 

Grate surface to cross section of flues.... 3.36 
Cross section flues to chimney 75 

DATA FROM THE TRIAL. 

Duration of trial 9 hours. 

Temperature of atmosphere '. 73.8° 

Temperature of water to boiler 146.5° 

Pressure by steam gauge (corrected) 93.93 

Water delivered to boiler 4965. lbs. 

Water entrained •. None. 

Coal fired 594.5 lbs. 

Ash and clinker returned 37.5 lbs. 

RESULTS OF TRIAL. 

Steam per pound of coal (from feed).... 8.35 lbs. 

Steam per pound of coal from and at 212° 9.25 lbs. 

Steam per pound of . combustible 8.906 lbs. 

Steam per square foot of heating surface per hour, 5.52 lbs. 
Coal fired per square foot of grate surface per 

hour 33.31 lbs. 

Percentage of non-combustible, in coal 6.3 

The boiler is entirely unprotected from loss of heat by 
radiation, and, according to Mr. J. C. Hoadley's deduc- 
tions, eleven per cent of the total heat developed was 
wasted in this direction ; whilst, had the boiler been well 
protected by brick side and end walls and overhead arch? 



294 A TREATISE ON STEAM BOILERS. 

with an air space between the brick-work and surfaces of 
boiler, the loss by surface radiation would have been 
reduced to about three per cent, and with other conditions 
the same, the trial would have developed an evaporation 
per pound of coal from and at 212° Fahrenheit of ^-^.f^^^ 
=10.07 pounds. 

Several years ago Mr. Hill made a series of evaporation 
trials on five small locomotive fire box boilers, the heating 
surfaces in which were, for the 

First boiler.. 95 sup. feet. 

Second boiler 85 sup. feet. 

Third boiler 102 sup. feet. 

Fourth boiler 84 sup. feet. 

Fifth boiler 85 sup. feet. 

And the evaporation per pound of Pittsburg coal, from 
and at 212° Fahrenheit, was for the 

First boiler 6.00 lbs. 

Second boiler 5.07 lbs. 

Third boiler 5.54 lbs. . 

Fourth boiler 6.12 lbs. 

Fifth boiler 6.44 lbs. 

Taking the average evaporation of these five boilers at 
5.83 pounds, then by this data the Suiter's boiler is capable 
of doing (f.ff = 1.585) nearly sixty per cent more work> 
or furnishing sixty per cent more steam with the same 
expenditure of coal. 

Taken together, the heating surface was less and the 
grate surface more in the five boilers mentioned than in 
the Suiter's, and by the ordinary methods of estimating 
boiler capacity, would be reckoned equal in power to the 
Suiter's ; hence the comparison of economic effects is fair, 
and exhibits the relative value of the latter boiler in a 
striking manner. 



PORTABLE ENGINE BOILERS. 



295 



During the trial the handling of the coal was not the 
best possible, and the boiler was set in the building in 
such a manner that the air currents freely circulated 
around, facilitating the absorption of heat by the atmos- 
phere from the naked surfaces of the arrangement. 

Mr. Hill says : " Considering the size of the boiler, 
I regard the economy obtained as excellent ; and am of 
the opinion that there is merit sufficient in it to justify the 
construction and trial of similar boilers of larger dimen- 
sions." 

The question of durability and facility of repair can 
only be determined by continuous use for a reasonable 
length of time. 

Portable boilers — The demand for a portable engine for 
agricultural purposes has been increasing for many years 




Figure 84. 



past, and is now a very large and important branch of 
industry. The boilers supplied with this class of engines 
are often of some one of the vertical tubular varieties, but 
more generally a modification of the locomotive type. 



296 



A TREATISE ON STEAM BOILERS. 



Figure 84 is a sectional elevation of a boiler designed by 
the writer for the Atlas Engine Works, Indianapolis, Ind. 
There are several hundred of them nov^ in use, and, with 
proper care, form a very good and serviceable kind of boiler 
for the purpose intended. 

The writer does not wholly approve of the water bot- 
tom to the fire box. This was made so originally in order to 
meet the requirements of Southern planters for use in or 
around their cotton gins; they were apprehensive that open 
bottoms, fitted with the ordinary ash pans, might endan- 
ger their premises, and required something which seemed 
to offer a better security against fire. 

This boiler is fitted with a fire box, having an arched 
top and strengthened by means of stay bolts, as shown in 
the engraving. The reversing of the head at the fire box 
was done to secure better riveting_and calking. This 
boiler steams rapidly and is very economical in the use of 
fuel. The following are the principal dimensions, as sup- 
plied with portable engines. The latter size is not usually 
supplied with wheels, but mounted on skids instead. It 
can be mounted, however, if desired : 

TABLE LXXXI. 

PRINCIPAL DIMENTIONS OF PORTABLE BOILERS. 





HORSE POWER 






8 


10 


15 


Diameter of boiler 


26 in. 
• 8 ft. 
30 in. 
33 in. 
21 in. 
19 
4J ft. 


28 in. 
8 ft. 7 in. 
30 in. 
34 in. 
23 in. 
27 
5 ft. 


30 in. 


Length of boiler 


10 ft. 


Length of fire box 


40 in. 


Height of fire box 


40 in. 


Width of fire box 


26 in. 


No. of 2^-inch tubes 


28 


Length of tubes 


6 ft. 







SEMI-PORTABLE BOILERS. 



297 



In some " practical " tests made at the works with very 
inferior coal as fuel, and feed water at a temperature of 65° 
Fahrenheit, the eight horse power boiler evaporated twelve 
cubic feet of water per hour, the ten horse power evapo- 
rating fifteen cubic feet in the same time. The evapora- 
tion was under a pressure of eighty pounds per square 
inch. The boilers were in the condition usually delivered 
to the trade, and the test was as near as possible the same 
as the firing would have been in the hands of the purchaser, 
except that it was conducted with a view to ascertain the 
actual evaporative capacity of the boiler instead of an 
economy trial. 

TABLE LXXXII. 

SEMI-PORTABLE BOILERS BY ATLAS ENGINE WORKS. 



ENGINE. 


HORSE POWER. 




15 


20 


25 


30 


40 


Diameter of cylinder .... 
Length of stroke 


8 in. 
12 in. 

160 
30 in. 
10 ft. 
40 in. 
40 in. 
26 in. 

28 

6 ft. 
16 in. 
18 in. 
12 in. 
20 ft. 


9 in. 
14 in. 

150 
32 in. 
12 ft. 
54 in. 
45 in. 
28 in. 

28 

7 ft. 
18 in. 
20 in. 
12 in. 
20 ft. 


10 in. 
16 in. 
140 
36 in. 
12^ ft. 
54 in. 
48 iTi. 
32 in. 

38 
7* ft. 
20 in. 
22 in. 
14 in. 
25 ft. 


10 in. 

20 in. 
120 

40 in. 

13 ft. 

54 in. 

49 in. 

36 in. 
49 
8 ft. 

24 in. 

24 in. 

16 in. 

30 ft. 


12 in. 

20 in. 


Revolution s 


120 


Diameter of boiler 

Length of boiler 


42 in. 
15 ft 4 in. 


Length of fire box 

Height of fire box 

Width of fire box 

No. of 2J inch tubes 

Length of tubes 


54 in. 

50 in. 

37 in. 
58 
9 ft. 


Diameter of dome 

Height of dome 

Diameter of stack ,. 

Length of stack 


• 24 in. 
24 in. 
20 in. 
30 ft. 







298 



A TREATISE ON STEAM BOILERS. 



The above table gives the proportions for boilers of 
the same style, but of larger sizes. 

Locomotive boilers — It is not within the scope of the 
present work to enter into the details of locomotive con- 




FiGURE 85. Class A. 



struction, in which the boiler figures so largely. Much 
that has already been said in regard to boilers in general 
applies to locomotives. There are also many details of 
contruction, which are peculiar to different builders 
and to certain roads. These could not be entered into 
without departing from the original purpose of the writer. 
It will suffice, perhaps, to give in brief outline the princi- 
pal dimensions of the locomotive boilers in use on the 




Figure 



Class B. 



Pennsylvania railroad as a guide merely for the propor- 
tioning of this kind of boilers for stationary uses. A 
short description is appended to each engraving to show 



LOCOMOTIVE BOILERS. 



299 



the particular service for which each class of engine is 
intended. 

In using the proportions in the table for stationary 
purposes the size of the boiler is about right for single 
cylinder engines of the sizes given in the table, if used 
with natural draft. The combustion of fuel is not as econ- 




FiGURE 87. Class C. Anthracite. 



omical "on the road" as when the rate is lower; which 
would be the case when used with ordinary chimney or 
force draft. 

Figure 85 is a representation of the boiler used with 
engines in class A, 17X24 cylinders, which are the one& 
employed for passenger trains on the main line, except in 




Figure 



Class C. Bituminous. 



the mountain districts. The principal dimensions are given 
in table LXXXIII. The shell and fire box of this class 
of boilers, and, indeed, all the boilers on this road, are 



300 



A TREATISE ON STEAM BOILERS. 



wholly of steel ; the tubes are, in all cases, of wrought 
iron, lap welded. 

The boilers in class B are somewhat larger than in class 
A, and supply 18X24 cylinders. These engines are used 
mainly in the mountainous districts for passenger service. 




Figure 89. Class D. 

The driving wheels are sixty-two inches diameter as against 
sixty-eight in class A. The tubes are increased in number 
and decreased in length over class A; the total heating 
surface being nearly the same. 

There are two styles of boilers for the engines coming 
within class C. The one represented in figure 87 is for 




Figure 90. Class E. 



burning anthracite coal, and the one in figure 88 is for 
bituminous coal. The cylinders for both styles of boilers 
are 17X24. This engine is used for passenger, local and 
fast freight trains. The number and size of the tubes vary 



LOCOMOTIVE BOILERS. 



301 



between these two boilers, a smaller tube being used for 
the anthracite than for the bituminous coal. The rate of 
combustion being slower for the anthracite coal, the grate 
is of larger area, and the heating surface in the fire box 
increased nearly forty per cent. The tube area is some- 




FiGURE 91. Class F. 



what less than for bituminous coal. The total heating 
surface divided by the fire grate area is 60.5 for the bitu- 
minous, and 39.86 for the anthracite burning boiler. The 
driving wheels are sixty-two inches diameter. 

The engines in class D are intended for ordinary freight 
service. The tubes are larger in diameter than for any of 




Figure 92. Class G. 



the boilers preceding it and of greater length. The fire- 
grate area is also less, the grate bars being but sixty inches 
in length ; the total heating surface in the fire box being 
ninety-six feet as against one hundred and fifteen in class 
C, bituminous. The cylinders in engines of this class are^ 



302 



A TREATISE ON STEAM BOILERS. 



18X22, with six driving wheels, fifty-six inches in diameter. 

The engines in class E are intended for freight service 
in the mountain districts. The cylinders are the same as 
for class D, viz, 18X22. The drivers are six inches less in 
diameter. The tubes are longer than in class D, as is also 
the length of the fire box. The total heating surface in 
this boiler is greater than any preceding it, except class C, 
anthracite. 

The boilers in class F differ from those already referred 
to, in the absence of the "camel back." This does not 
reduce the width of the fire box, but does reduce the 
height. This engine is used for making up trains and for 




Figure 93, Class H. 



general yard service. The cylinders are 15X18 inches, the 
driving wheels are 44 inches diameter. The tank is placed 
over the boiler, as shown. 

The engines in class G are used for passenger service 
on branch lines. The cylinders are 15X22 inches, and have 
56-inch driving wheels. 

This is a good form of boiler to use for stationary 
engines. The writer prefers it to what is known as the 
camel back, as shown in figures 85 to 90. As the rate of 
combustion is less when used in a building from what it 
would be " on the road," the fire box might be lengthened 
if thought necessary. 



EnOINE' 



Thickness of boiler platei 
Thickness of boiler plate 
Thickness of boiler plate; 
Maximum internal diamt 
Maximum internal diamt 
Height from top of rail t( 

Number of tubes 

Inside diameter of tubes. 
Outside diameter of tubei 
Length of tubes between 
Number of internal diam 
Length of fire box at bot1 
Width of fire box at bott 
Height of crown sheet ab 
Thickness of inside fire b 
Thickness of inside fire b 
Thickness of tube sheets, 

{Diameter of cy 
Length of strot 

H 

External heating surface 
Internal heating surface c 
Fire area through tubes.. 

Firegrate area 

Heating surface of fire bo 
Total heating surface witl 
Total heating surface witl 
External tube surface div 
Total heating surface divi 
Fire grate area divided bj 
Diameter of smoke stack., 
Least sectional area of ch 
Fire Grate area divided 
Pressure of steam per squ 
Effective pressure per squ 

Capacity of tank 

Capacity of coal tank... 



CLASS 

o, 

PASSENGER 

ENGINE. 



CLASS 

H, 

SHIFTING 

ENGINE. 



5 
T6 

Vs 

% 

44% 
70 
130 

1% 

2 

115 

65.7 

64% 

35 

52% 

5 

3^ 

15 
22 

652.31 sq. ft, 

574.0 sq. ft, 

2.17 sq. ft, 

13.3 sq. ft. 

69.04 sq. ft. 
721.35 sq. ft. 
640.04 sq. ft. 

9.44 

.')4.23 

6.13 

17 in. 

1.58 sq. ft. 

8.50 

125 lb."*. 

100 lbs. 

1,600 gals. 

6,500 lbs. 



5 
T6" 

Vs 

% 
47% 
U% 
63>^ 

91 
2% 
2% 
156% 
69.5 
54.5 

35 
46>^ 

5 

TS" 

15 

22 

776.13 sq. ft. 
699.79 sq. ft. 
2.51 sq. ft. 
13.2 sq. ft. 
79.11 sq. ft. 
855.24 sq. ft. 
778.90 sq.ft. 
9.80 
64.79 
5.25 
15 in. 
1.23 sq. ft. 
10.8 
125 lbs. 
100 lbs. 
2,200 gals. 
5,000 lbs. 



CLASS 

I, 
FREIGHT 
ENGINE. 



5 

% 

7 

.55% 

53% 

77 

138 

2>i 

2^ 

153 

68.1 

96 

34% 
43>i 



•^M 



5 
TS 

20 
24 

1,158.65 sq. ft. 

1,043.28 sq. ft. 

3.75 sq. ft. 

23.0 sq.ft. 

100.91 sq. ft, 

1,259.56 sq. ft. 

1,144.19 sq. ft. 

11.48 

54.76 

6.16 

20 in. 

2.18 sq. ft, 

10.54 

125 lbs. 

100 lbs. 

3,000 gals. 

8,000 lbs. 



\. 



TABLE LXXXIII. 

LOCOMOTIVE BOILERS, PENNSYLVANIA RAILROAD. 



Thickness of boiler plat«s, barrel and dome 

Thickness of boiler plates, outside fire box slope 

ThiekQessof boiler plates, waist and smoke box 

Maximum Internal diameter of boiler 

Maximum internal diameter of wagon top 

Heightfrom top of rail to center of boiler 

Number of tubes 

Inside diameter of tubes 

Outside diameter of tubes 

Length of tubes between sheets 

Number of internal diameters in length of tube 

Length of fire box at bottom (inside) 

Width of fire box at bottom (inside) 

Height of crown sheet above top of grate 

Thickness of inside fire box sheets, sides 

Thickness of inside fire box sheets, front, back and crown 

Thickness of tube sheets 

{Diameter of cylinder 
Length of stroke 

HEATING SURFACE. 

External heating surface of tubes 

Internal heating surface of tubes 

Fire area through tubes 

Firegrate area 

Heating surface of fire box 

Total heating surface with external area of tubes 

Total heating surface with Internal area of tubes 

External tube surface divided by fire box area 

Total heating surface divided by fire gi^te area 

Fire grate area divided by tube area 

Diameter of smokestack 

Least sectional area of chimney 

Fire Grate area divided by least sectional area of chimney 

Pressure of steam per square inch 

Effective pressure per square inch estimated at g boiler pressure- 
Capacity of tank 

Capacity of coal tank 



66% 
35 
60% 



920.52 ,sq. ft. 

815.4 sq. ft. 

3.16 sq. ft. 

16.1 sq. ft. 

131.72 sq. ft. 

,052 24 sq. ft. 

947.12 sq. ft. 

6.98 

65.36 

5.09 

18 in. 

1.77 sq. ft. 

9.11 

125 lbs. 

100 lbs. 

2,400 gals. 

8,000 lbs. 



% 
% 
51-% 



2Ji 



63.5 



601^ 

}4 



941 .87 sq. ft. 

858.70 sq. ft. 

3.37 sq. ft. 

17.6 sq. ft. 

115.11 sq. ft. 

1,066.98 sq. ft. 

973 51 sq. ft. 

8.18 

00.5 

5.22 

18 in. 

1.77 sq. ft. 

9.96 

125 lbs. 

100 lbs. 

2,400 gals. 

8,000 lbs. 



BITUMINOUS 

PASSENGER 

ENGINE. 



% 
51% 
48iJ4 



911.87 sq. ft, 
858.70 sq. ft, 
3..37 sq. ft, 
17.11 ,sq. ft. 
115.11 sq. ft. 
1,056.98 sq. ft. 
73.51 sq. ft. 
8.18 
60.5 
5.22 
18 in. 
77 sq. ft. 

9.96 
126 lbs. 
100 lbs. 
i,400 gals. 
5,000 lbs. 



ANTHRACITE 

PASSENGER 

ENGINE. 



% 



125fk 
71.7 
119% 
34^ 
44 



1,002.60 sq. ft 

878.45 sq. ft, 

3.06 sq. ft 

29.13 .sq. ft, 

1.68.56 .sq. ft. 

1,161.15 sq. ft. 

1,036.95 sq. ft. 



18 in. 

1.77 sq. ft. 

16.48 

125 lbs. 

1011 lbs. 

2,40(1 gals. 

8,000 lbs. 



% 
50% 



2X 



67.5 
69J^ 



57% 



997.25 sq. ft, 

886..65 sq. ft, 

3.28 sq. ft, 

14.6 sq. ft, 

95.97 sq. ft, 

1,093.22 sq. ft. 

982.52 sq. ft. 

10.39 

75.38 

4.42 

18 in. 

1.77 sq. ft. 

8.20 

125 lbs. 

100 lbs. 

2,400 gals. 

8,000 lbs. 



% 
% 
51K 

48% 



2J4 
2% 



146tt 






64.9 






6714 






35 






57^ 






X 






6 






18 






22 






984.83 sq 






885.6 sq 






3.39 sq 






16.34 sq. 






111.27 .sq. 






,096.10 sq. 


ft. 




996.87 sq. 


ft. 




8.85 






67.18 






4.85 






18 in. 






1.77 sq. ft 






9.24 






125 lbs. 






100 lbs. 






2,400 gals 






8,000 lbs 







Vs 

% 

43% 
42% 
63K 



74.5 
44Ji 



651.22 sq. ftl 

678.5 sq. ft 

1.93 sq. ftl 

10.7 sq. ft; 

61.29 sq. ft, 

712.51 sq. ft. 

639.79 sq. ft; 

10.62 

66.59 

5..54 

15 in. 

1.23 sq. ft. 

8.72 

125 lbs. 

101) lbs. 

820 gals. 

1,500 lbs. 



% 
44% 



m 



66.7 

64% 



52% 



652.31 sq. ft 

574.0 sq. ft 

2.17.si|. ft 

13.3 sq. ft, 

69.04 sq. ft, 
721.35 sq. ft. 
640.04 sq. ft. 

9.44 

54.23 

6.13 

17 in. 

1.58 sq. ft. 

8.,60 

125 lbs. 

100 lbs. 

1,600 gals. 

6,500 lbs. 



% 

% 
47^ 
44% 
633^ 

91 
2% 

2K 



46K 



776.13 sq. ft, 

699.79 sq. ft. 

2.61 sq. ft. 

13.2 sq. ft. 

79.11 sq. ft. 

855.24 sq. ft. 

778.90 sq. ft. 

9.80 

64.79 

5.25 

15 in. 

1.23 sq. ft. 

10.8 

125 lbs. 

100 lbs. 

2,200 gals. 

5,000 lbs. 



65% 
,53% 



2Ji 
2>^ 



43^ 



1,168.65 sq. ft. 

1,043.28 sq. ft. 

3.75 sq. ft. 

23.0 sq. ft. 

100.91 sq. ft. 

1,259.56 sq. ft. 

1,144.19 sq. ft. 

11.48 

54.76 

6.16 

20 in. 

2.18 sq. ft. 

10.54 

125 lbs. 

100 lbs. 

3,000 gals. 

8,000 lbs. 



LOCOMOTIVE BOILERS. 



303 



The boilers in class H are very similar to those in class 
F. The boilers are larger in diameter, as are also the 
diameter of the tubes. The firebox is about ten inches 
longer. The cylinders are 15X22 inches. The driving 
wheels are forty-four inches in diameter. 




Figure 94. Class I. 



The engines belonging to class I are represented in 
figure 94. This is the largest and heaviest class of engines 
in use on this road. The boilers are peculiar in their 
construction, as seen from the above engraving. These 
engines are for heavy freight service in the mountain dis- 
tricts. The cylinders are 20X24 inches. The driving 
wheels are 50 inches in diameter. For the constructive 
details of this engine and boiler, and for the others already 
given, the reader is referred to ''Engineering," volume 24 
or to '^ The Pennsylvania Eailroad," which is a reprint of 
the articles contained from week to week in "Engineer- 

iDg." 

The principal dimensions of these boilers are collated 
from the tables published in Engineering, and given in 
table LXXXIII, which may be of very great service to 
those interested in boilers of this type. 



\. 



CHAPTER XII. 



BOILER SETTING. 

Ordinary Boiler Settings — Grates — Force Draft — Resistance of Air in 
Passing through Pipes — Sizes of Pipes required for Grate Areas — 
The Jarvis Furnace — The Butman Furnace — The Pierce Furnace. 

After deciding which kind of a boiler is best adapted 
for any particular service, the question of boiler setting 
should then be carefully con- 
sidered. There are all sorts of 
ideas as to how a boiler should 
be set; many of them good 
and quite as many more at 
variance with the actual re- 
quirements. It matters little 
what the particular design of 
the furnace may be, if it affords 
complete combustion. The 
requirements in furnace con- 
struction have already been presented in Combustion of 
Coal, to which the reader is referred, particularly to 

Chapter V, on combustion. 

Chapter YI, on air required for furnace combustion. 

Chapter YII, on the furnace. 

Chapter YIII, on the products of combustion. 

A very common form of boiler setting is shown in 
figure 96, where but little money is to be expended in its 
erection. It is by no means the ideal furnace ; yet it fur- 
nishes good evaporative results when properly fired. 




Figure 95. 



BOILER SETTING. 



805 



The following table gives the ordinary proportions ; the 
letters in the table are those corresponding to dimension 
lines as given in the engraving bearing the same letters : 




k^£_> 



Figure W. 



TABLE LXXXIV. 

PROPORTIONS FOR FLUE AND TUBULAR BOILER SETTINGS. 
A II dimensions are in inches. 



A. 


B. 


"■[ 


D. 


E. 


F. 


G. 


H. 


I. 


J. 


K. 


L. 


M. 


N. 


O. 


p. 


Q- 


K. 


s. 


T. 


U. 


V. 


w. 


X. 


Y. 


z. 


36 


144 


■25 


170 


18 


48 


42 


18 


44 


18 




16 


18 


51 


9 


13 


16 


81 


13 


24 


45 


13 


oil 


71 


74 


24 


38 


144 


■25 


170 18 


48 


42 


18 


44 


18 




16 


20 


51 


9 


13 


16 


82 


13 


24 


47 


13 


51 


73 


75 


24 


40 


144 


25 


1 
170 18 


48 


42 


18 


44 


18 




16 


20 


51 


9 


13 


16 


84 


13 


24 


49 


13 


51 


75 


76 


24 


42 


144 


21 


170 18 


52 


46 


18 


44 


18 




16 


20 


51 


9 


13 


16 


85 


13 


24 


51 


13 


55 


77 


77 


24 


44 


144 


21 


1 
170 18 


52 


46 


18 


44 


18 




16 


20 


51 


9 


13 


16 


86 


13 


24 


53 


13 


55 


79 


78 


24 


46 


144 


21 


170 18 


52 


46 


18 


44 


18 


If 


16 


20 


51 


9 


13 


16 


88 


13 


24 


55 


13 


55 


81 


79 


24. 


4S 


144 


21 


170 


18 


52 


46 


18 


44 


18 


« 


16 


20 


51 


9 


13 


16 


89 


13 


30 


57 


13 


55 


83 


80 


24 


50 


144 


13 


170 


18 


60 


54 


18 


44 


18 


2 


16 


20 


51 


9 


13 


16 


90 


■13 


30 


59 


13 


63 


85 


81 


24 


52 


144 


13 


177 


18 


60 


54 


18 


44 


18 


02^ 


16 


20 


51 


9 


13 


18 


?2 


18 


30 


61 


18 


63 


97 


82 


24 


54 


144 


13 


177 


18 


60 


54 


18 


44 


18 




16 


20 


51 


9 


13 


18 


93 


18 


30 


63 


18 


63 


99 


83 


24 


56 


144 


1 


177 


18 


72 


66 


18 


44 


18 




16 


20 


51 


9 


13 


18 


94 


18 


30 


65 


18 


75 


101 


84 


24 


58 


144 


1 


177 


18 


72 


66 


18 


44 


16 




16 


20 


51 


9 


13 


18 


96 


18 


30 


67 


18 


75 


103 


85 


24 


60 


144 


1 

i 


177 


18 


72 


66 


18 


44 


18 




16 


20 


51 


9 


13 


18 


97 


18 


30 


69 


18 


75 


105 


86 


24 



(21) 



306 



A TREATISE ON STEAM BOILERS. 



The distance given in column D is from the center of 
the cast iron front to the back end of the rear wall. 

The distance E is intended to be that of two bricks. 
There are sections of the country where bricks will not 
lay to nine-inch centers. In any such case the thickness 




Figure 97. 



This will 



may be varied to suit the size of the bricks, 
apply to columns H, J, P, S and V. 

The distance K will vary with the diameter of the mud 
drum, if one is used. The drum may, in general, be one- 
third the diameter of the boiler and may extend from out- 
side to outside of the walls and should always be fitted 
with a man hole. In building the wall, proper allowance 
must be made for expansion. Figure 97 shows a mud 




Figure 98. 

drum suitable for a' single setting and figure 98 for a dou- 
ble setting. Sometimes the mud drum is placed in the 
direction of the boiler instead of across it ; in that case 
the nozzle is fitted at one end of the drum, the other end 
passing out through the rear wall. 



BOILER SETTING. 307 



The distance given in column L is that, when the noz- 
zle is riveted to the second sheet from the rear end, where 
the sheets have twenty-four inch centers. 

The thickness, S and V, are for single walls, but double 
walls are recommended instead, as being more economical 
in fuel. The distance W is that from the face of the bridge 
wall to the inside of the fire front. The grate bars have a 
"rest" of about one inch at each end on the bridge wall 
plate and on the bearing bar attached to the. fire front. 
The fronts are intended for separate breechings to be 
attached to the boiler. When a smoke box is formed by 
a continuation of the shell, a deeper lining around the fire 
will be required if the front is brought out "fiush" with 
end of the boiler. This will also change distances D andG 
as well as W. 

The distance, Z, is to the under side of the grate. The 
engraving shows the grate bars slightly depressed at the 
back end. This a very common practice in setting grates. 
The writer does not attach any special importance to it. 

The distance from the under side of an externally fired 
boiler to the top of the grates will vary with the kind of 
fuel to be burned. For bituminous coal, so far as the 
writer's observation goes, thirty inches appears to be the 
best distance. 

There are several "batteries"' of boilers known to the 
writer in which the distance is thirty-six inches, and in 
one instance forty-eight inches. It is not apparent that 
anything is gained by this extra distance over thirty 
inches. For semi-bituminous coal the distance may be 
twenty to twenty-four inches, and for hard anthracite 
about eighteen inches. These distances may be varied 
somewhat to suit local conditions. 

The furnace walls, as shown in figure 95, are brought 
in to the boiler sides on the line of the diameter. It is 
recommended that they be carried up to the water line or 
just below it, and thus increase the heating surface. 



308 A TREATISE ON STEAM BOILERS. 

It will be observed that the longitudinal dimensions are 
for boilers twelve feet long in all cases. In whatever 
amount the boiler is longer than that distance, columns B, 
C and D only are changed, unless the rear support to the 
boiler is to be brought nearer the furnace, in which case 
the distance, L, will be increased and C decreased. 

This setting has a cast iron plate at the back end of the 
boiler, instead of being arclied, as is sometimes the case, 
and shown in figure 105. 

The writer prefers a plate, especially for tubular boil- 
ers, as it enables the end of the tubes to be quickly got at 
for repairs or examination and affords a good light at the 
same time. No objection exists, however, to the brick 
arch, and it may be commended for the facility which it 
affords the return of the gases through the tubes or flues. 

The walls are carried up, as shown in the engraving, 
and filled in over the top of the boiler with some good 
non-conducting material. There are a number of good 
non-conductors in the market, which may be used, or a 
brick arch may be carried over the top of the boiler. This 
arch may rest upon a thin wooden lining laid over the top 
of the boiler. AYherever brick work is to come> in contact 
with the sbell of the boiler, the joints should be made with 
fire clay instead of lime mortar; fire clay should also be 
used with fire brick in the furnace. 

Brick should be used throughout in the boiler setting, 
and is to be preferred to stone for the foundations. 

There are localities in which boilers are seldom or 
never set in the manner shown in figure 96, but have roll- 
ers underneath, as shown in figure 105; or rest upon the 
side walls, the boilers having cast iron lugs riveted to the 
shell, as shown in figure 61. The writer has fitted them 
in each of the styles indicated, but prefers the mud drum, 
either as shown, or passing out through the rear wall. 



RYDEll't^ GRATE BAR. 309 

The grate surface is composed alternately of solid metal 
and free spaces in about equal areas, or, perhaps, the solid 
metal slightly exceeds the spaces. The grates should have 
depth instead of width for the needed strength. It is cus- 
tomary to make the grates of cast iron, though bars of 
inch or inch and a quarter square iron are often used. For 
burning anthracite coal a grate made of wrought iron 
tubes, through which the feed water is made to pass, has 
been used with good results. A modilication of this grate 
is frequently applied to locomotives. 

The ordinary grate bar is too well known to need any 
description. Figure !H) is an engraving of a grate bar 
made by Albright Sc Stroh, Mauch Chunk, Pa. This grate 




FiGUKR ilO. 



bar may be used with coal, wood or sawdust, and presents 
more free space than is usual for grates of this class; it is 
of liofht w^eio;ht, and after a trial it has been found to with- 
stand warping in heavy tiring. 

The clearing of tires by means of slice bars and hooks 
is a very difiicult and exhausting kind of labor, especially 
if the grates are of any considerable length. The radiant 
heat from an open furnace door during the hot summer 
months is very trying, and none but experienced tiremen, 
as a rule, can stand it. 

Ryder's reciprocal gratehars — Figure 100 is an engrav- 
ing of a grate bar manufactured by Mr. J. F. Montgomery, 
Taunton, Mass., and is known as Kyder's patent reciprocal 
grate bar, which was designed to overcome this labor- 
ious and ditiicult operation. These bars are simple in 
construction, and consist of a series of movable and sta- 
tionary bars. The movable bars (ev^ry other one being 



310 



A TREATISE ON STEAM BOILERS. 



stationary) are moved backward and forward several 
inches by a lever in front of the boiler, through the ash 
pit door. The movable bars resting on friction rolls are 
raised above the stationary bars a little, and have a cor- 
rugated surface for friction, which thoroughly disturbs the 
coal, destroys the clinkers and removes all the ashes, thus 
opening up a thorough and uniform draft over the entire 




Figure l^U. 



tire surface. By the uniformity of draft and ventilation 
thus gained, a more perfect combustion of all the gases is 
obtained. 

Steamship engineers and (iremen of long experience 
sailing out of New York and Boston, and ihose who are 
running stationary engines and boilers with these bars, 
report excellent I'csults in the economy of coal, and that an 
easv ireneration and unitbrm pressure ot steam is obtained 
with lii^ht lires — tiring often with little coal at a time. 



RYDER S GRATE BAR. 



311 



The bars should be worked as often as appears necessary 
to keep the fire clear from ashes and clinkers. The danap- 
ers in the flues should be kept well closed, in order to 
intensity the heat and retain it in contact with the heating 
surface of the boiler and tubes, instead of rapidly forcing 
it tlirough them by strong draft, and out of the smoke 
stack or chimney, with the gases of the coal half consumed, 
thus wasting nearly one-half the value of the coal. 

Keeping the damper closed as much as possible is a 
good practice at all times. The writer has referred to it 
once or twice previously in this book. 

It is claimed that the reciprocal grate bars develop a 
new and successful method 
for the ventilation of fires, 
as they produce a level sur- 
face of coal over the entire 
grate, ensuring, by the re- 
ciprocal action, a uniform 
or equal consumption of 
coal ; that the bars will not 
warp or crook: that with 
three vibrations of the 
lever, more execution can 
be performed in the ven- 
tilation and cleaning of the 
fire, than by the use of the 
poker or slice bar in one 
hour's time; that abetter 
fire can be obtained, with 
less draft back of the 
bridge wall, less fuel and 
less labor than with any 
other bars in use, and no 
loss (but a gain) in steam, figure loi. 

while cleaning fires, as the fire doors are never open wiiile 
cleaning them. 




312 



A TREATISE ON STEAM BOILERS. 



Force draft — In case the draft should be deficient or 
sluggish, a steam jet or blast nozzle may be used with 
advantage, something like the one shown in figure 101, and 




placed in the interior and at the base of the chimney, as 
shown. This is not equal in efiiciency to the forcing of 
the air under the grates. This usually requires some 
special adaptation of the apparatus to the ash pit or fur- 
nace and is not so easily or cheaply applied, but in the 
"long run" there is economy by so attaching it, if it is to 
be a permanent fixture. Figure 102 represents one form 
of apparatus for a force draft, as designed by Schutte & 



FORCE DRAFT. 



313 



Goehri ng, Philadelphia, Pa. Figures 101 and 103 are also 
bj the same firm. 

AVhen the blower is attached below the grates, as shown 
in figures 102 and 103, tbe ash pit must be fitted with a 
close fitting door, that the pressure of the air be compelled 







^^^^^/^^ 



i«%% ;?^%««S%S« %5?«S4i«««% «S«%S5^^ 

%%%%?J2i9 ■''/////'■////yK '^/y//yy////A %y<!%%% :%%a% ^ mcz^/x^. :4%?«%«%4 %j!S;?%%5^ V/^//////////. v/z/y/xm!:. 
Figure 103. 



to pass up through the fire, instead of forcing its way into 
the fire room. By the use of a force draft economy of 
fael is attained by a more perfect combustion, and wiiroften 
permit the use of a refuse fuel which could not be burned 
in an ordinary fire. It also permits the use of a lower and 
less expensive chimney, which becomes simply an exit for 
the escaping gases The quantity of air to be admitted to 



314 



A TREATISE ON STEAM BOILERS. 



the fire may be adjusted by means of the valve in the 
steam pipe at A, the supply of air being admitted through 
the pipe B. Figure 103 shows the application of the 
blower to a Cornish boiler. 

This firm make four sizes of these blowers, with capa- 
cities as follows: 



I 



TABLE LXXXV. 

STEAM JET BLOWERS FOR BOILER FURNACES, BY 8CHUTTE AND 

GOEHRING. 





CAPACITY. 


DIAMETER 

OF 

STEAM PIPE. 




SIZE. 
NO. 


AIR REQUIRED 

PER HOtJR, 
IN CUBIC FEET. 


COAL CONSUMED 
PER HOUR, 
IN POUNDS. 


DIAMETER OF 

AIR DISCHARGE 

AND INLET. 


1 

2 

3 
4 


30,000 

60,000 
120,000 
200,000 


150 

300 

600 

1,200 


^2 inch. 
4 inch. 
1 inch. 
1 inch. 


6 inch. 

8 inch. 
10 inches. 
14 inches. 



A fan blower is often used for the purpose of supply- 
ing air to the ash pit, and serves a good purpose. The only 
objection to such an arrangement is, that it must be actu- 
ated by moving machinery, which is not always at hand ; 
but whenever it is convenient to make suitable attachments 
it may be used with advantage. Blast ga,tes should be 
used in all cases and inserted in the blast pipe at any point 
most convenient for adjustment. When two or more boil- 
ers^are placed in the same setting, there should be a branch 
pipe and gate for each boiler. The sizes of blast pipes 
required, as given below, are for one furnace; where two 
or more are connected and supplied from one main pipe, 
its size can be obtained by reference to table LXXXYII. 
The following data is from the catalogue ot" Mr. B. F. 
Sturtevant, Boston, Mass. : 



EQUALIZING THE DIAMETER OF PIPES. 



315 



TABLE LXXXYI. 

SHOWING DIAMETER OF PIPES REQUIRED FOR SUPPLYING AIR TO 

BOILER FURNACES. 



NO. OF 


CUBIC FEET 


DIAMETER 


NO. OF 


CUBIC FEET 


DIAMETER 


SQUARE 


OF AIR 


OF 


SQUARE 


OF AIR 


OF 


FEET 


TO BE 


BL.\ST PIPE 


FEET 


TO BE 


BLAST PIPE 


OF (JRATE 


SUPPLIED 


REQUIRED, 


OF GRATE 


SUPPLIED 


REQUIRED, 


SURFACE. 


PER MINUTE. 


IX INCHES. 


SURFACE. 


PER MINUTE. 


IN INCHES. 


1 


125 


3,^ 


8. 


1,000 


8i 


O 


250 


4i 


9 


1,125 


9 


•-> 
■J 


375 


H 


10 


1.250 


9| 


4 


500 


6.] 


12 


1,500 


10 


5 


625 


t 


15 


1,875 


11 


C) 


750 


'>h 


20 


2 500 


12i 


7 


875 


8 


25 


3,125 


13* 



Mr. Sturtevant has given this subject a great deal of 
attention for many years, and has made many and costly 
experiments to determine the frictional resistance of air in 
passing through long tubes or pipes. The following table 
was calculated for the use of those putting up blast pipes, 
who, knowing little or nothing of the frictional resistance 
of the air, are apt to think that because the combined area 
of four 6-inch pipes is the same as one 12-inch pipe, that 
the four pipes will convey the same quantity of air, with 
the same ease and freedom, that the 12-inch will ; whereas 
it actually does take 5.7 — almost six 6-inch pipes. Again, 
sixteen 3-inch pipes have the combined area of one 12-inch 
pipe, but in actual practice it takes just thirty-two 3-inch 
pipes to do the work of one 12-inch. This is due to the 
excess of friction for every cubic foot of air in the small 
pipes over that in the large: 



316 



A TREATISE ON STEAM BOILERS. 







































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The large figures at the top of each column give the 
diameters in inches of the branch pipes. The figures at 



THE JARVIS FURNACE. 317 



the intersection of the horizonal line with the vertical give 
the number of pipes, of the diameter given at the top of 
the column, that will be equal in capacity for conveying 
air to one given opposite in the first column. 

The Jarvis furnace — This improved design in furnaces 
for steam boilers is that of Mr. K. M. Jarvis, Peabody, 
Mass.. and shown in lonHtudinal section in fi2:ure 104. 
The object Mr. Jarvis had in view in working out this 
design was, to take advantage of the quantity of heat escap- 
ing from the ordinary furnace and conapel it to perform a 
useful service, by heating the air required to complete the 
combustion of the fuel and gases evolved during the pro- 
cess of combustion. 

In order to accomplish this he utilizes the bridge wall 
and the back of the furnace, as well as the side walls, for 
the heating of the air to be discharged into the combustion 
chamber, hence the greater portion of the side walls are 
made double. By this arrangement in the construction, 
the air is delivered to the column of gases freed by the com- 
bustion of the coal, through the bottom and sides of the 
combustion chamber, the heated air acting to reduce the 
temperature of the gas much less than cold air, thus per- 
mittins: the oxvsren of the heated air to mins^le with the 
gas at a temperature nearer that of ignition, and by this 
means makino; the combustion more thorouo^h while the- 
gases are under the boiler and where the greatest heat is 
needed. 

The boiler may be either flue or tubular; the distance 
from the under side of the boiler to the grate may vary 
within reasonable limits, and may be from twenty-four 
to thirty inches. The grates may be of any of the com- 
mon or improved forms now in the market, and the fur- 
nace arranged for either slow or quick combustion. Back 
of the bridge wall, G, is an open space, C, covered from 



:318 



A TREATISE ON STEAM BOILERS. 



side to side with a perforated cast iron plate, sliown at 
in the engraving ; through these perforations passes heated 
air discharged from flues built in the wall or in the bottom 
of the furnace. The object in the introduction of this 
heated air is to mingle with the carbonic oxide gas while 
it is at a high temperature, and thus supply the oxygen 
needed to again convert it into carbonic acid gas, and thus 
render the combustion complete. The same thing may be 




FiGUR 



also secured, and is in part assisted, by the openings in the 
side walls, as shown in the engraving. These hollow walls 
also perform a useful service in preventing radiation. The 
details of this furnace are very carefully worked out and 
are yielding excellent results. 

The combustion of peat and lignite is one which will 
be of considerable importance in the far west, and in some 
of the northern states. The application of this furnace to 
the burning of peat has been attended with very success- 
ful results. Peat freshly dug from a marsh is mixed with 



THE JARVIS FURNACE. 



319 



one-fourth its bulk of small bituminous coal and thrown 
on the fire, and within a few minutes the gas flames begin 
to form on the flue openings, and presently the entire fur- 
nace is filled with flame, showing a practical gasification of 
the peat and a perfect combustion of the gases. Ko blower 
is needed, as the streams of hot air thrown on the fire 
create a good draught, and effectively consume the peat 
and with good results in steam power. 

TABLE LXXXVIIl. 



DESIGNATION OF EXPERIMENTS. 



Duration of test...; 

Pressure of steam .". 

Temperature of feed water, in degrees. 



Amount of water evaporated at temperature, in 
pounds 



Amount of coal consumed, in pounds., 



Am( unt of ashes 

Amount of combustible, in pounds. 



Pounds of water evaporated per pound of coal, at 
temperature of feed 



Pounds of water evaporated per pound of combusti- 
ble, at temperature of feed 



Pounds of water evaporated for one dollar's worth of 
fuel 



Cost of fuel consumed in time run'^- 

Gain in economy, in favor of Jarvis setting.. 
Gain in capacity, in favor of Jarvis setting... 



Pounds of water evaporated per pound of coal, at 212*^.. 

Pounds of water evaporated per pound of combusti- 
ble, at 212*^ 



8.46 

9.69 
9.93 

11.36 

4,742 
f 269. 60 



DECEMBER 

17 TO 23, 

OLD SETTING, 

EIGHT BOILERS. 


MARCH 

23 TO 31, 

JARVIS SETTING, 

SIX BOILERS. 


6 days and niglits. 


6 days and nights. 


63 


68 


78 


82 


1,278,682 


1/268,880 


soft coal, 
\ 151.060 


r soft coal, 
44.329 
J screenings, 
114.190 

I 158.519 


19.040 


15.698 


132.020 


142.821 



8.00 

8.92 
9.32 

10.39 

6,803 
$183.40 
30 per cent. 
25 per cent. 



'•'•Borden Cumberland coal, four dollars per long ton, delivered in Fall River. New 
York Cargo screenings, two dollars and thirteen cents per long ton, delivered in Fall River. 



320 



A TREATISE ON STEAM BOILERS. 



The above tests in evaporation were made at the 
American Linen Company, Fall River, Mass., under the 
following circumstances: eight 6-feet tubular boilers, 
running one-half of the mill, were tested, by weighing the 
water and coal for one week, night and day. The fuel 
used was Borden Cumberland coal. The boilers were then 
reset with the Jar vis patent furnace and tested again for 
the same time. The fuel used on the last test w^as a mix- 
ture of screenings and soft coal, burned without a blower. 
It only required six boilers, after the resetting, to do the 
same work that before required eight. 

This system of boiler setting is already in extensive 
use, and, in making it possible to burn peat with economy, 
will do much to utilize our vast stores of peaty fuel^ and 
tend to cheapen the cost of steam power. 

The Butman furnace — This improvement over the old 
style of setting steam boilers is the invention of Mr. T. 
R. Butman of Dayton, Ohio. The basis upon which the 
inventor rests his claims for success ai;e, 

1. The utilizing of the waste heat from the chimney, 
by furnishing a hot blast to the furnace. 

2. The supply of the proper amount of heated air 
directly to and in contact with the hydrocarbon gases at 
the moment they g^re evolved from the coal. 

3. A complete and perfect combustion of the products 
of distillation at the surface of the coal, resulting in a 
large volume of highly heated transparent gases flowing 
off in contact with the boiler. 

4. Such an arrangement of the furnace walls and pass- 
ages that the heated products of combustion are equally 
distributed to the surface of the boiler, causing a thorough 
absorption of the heat by the water, and also preventing 
any local concentration to burn the metal. 



THE PUTMAN FURNACE. 



321 



5. Because of the perfect combustion of the gases and 
carbon of the coal in the furnace. All smoke is positively 
prevented. 

6. Owing to the peculiar manner in which the com- 
bustion is eftected, all intense local heating of the brick 
walls and linings of the furnace are prevented, thereby 
ensuring great durability and a minimum cost for repairs. 




Figure 105. 



A longitudinal sectional elevation of the furnace is 
shown in figure 105. It will be observed that it does not, 
as shown in longitudinal section, materially difi:er from the 
ordinary setting in the main essentials. The boiler rests 
upon the front in the usual manner, and is supported at 
the rear end on a concave roller, which fits the shell of the 
boiler and is thus free to roll on a cast iron plate, having 
a similar curve and which is securely fastened to the rear 

(22) 



322 



A TEEATISE ON STEAM BOILERS. 



wall. The brick work is so designed that it forms a cover- 
ing over the top of the boiler and coming in contact with 
it at each end only. Referring to figure 105, it will be seen 
that there are (in this particular case) three pendants from 
the overhanging arch, which nearly but not quite touch 
the top of the boiler. These pendants continue around 
the top of the boiler and extend down to a short distance 
below the water line, forming thereby a series of small 




compartments over the top of the boiler — the object of 
these pendants being to prevent a circulation of heated 
gases over the top and thus compelling them to flow along 
the sides of the boiler below the water line, yet, at the 
same time, allowing the upper portion to be jacketed with 
hot gases having a temperature scarcely, if ever, greater 
than 500° Fahrenheit, 

A foundation plan of a single boiler setting is shown in 
figure 106. This shows the hollow walls to prevent radia- 
tion, and will be referred to again in connection with figure 
107. This plan shows the section at the line F, in figure 
105. 



THE BUTMAN FURNACE. 



323 



A horizontal section through the walls at the center of 
the boiler, is shown in figure 107. The distance from the 
side of the boiler to the inside line of fire brick at A is 
about three inches and gradually increases to the point 
B, then contracts again to C and thence to D, where the 
distance is a little greater than at A. These distances 
from the boiler to the walls at the points B, C, D, will 
depend upon the diameter and length of the boiler. The 




Figure 107. 



end wall is curved in order to prevent the forming of an 
eddy of gases at that point and to facilitate the flow of 
gases into the tubes or flues. 

The enlargement of the furnace at B, which is directly 
opposite the bridge wall at the rear end of grates, is for 
the purpose of forming a combustion chamber and which 
is better represented in figure 109. From this point to the 
rear end of the boiler the walls gradually contract in all 
directions toward the shell of the boiler and thus compel 
the escaping gases to come in closer contact by reason of 
the contracted area between the boiler and the walls of the 
furnace. Air. Butman claims that by this arrangement he 



324 



A TKEATISE ON STEAM BOILERS. 



prevents the bad effects of the localization of an intense 
heat at or near the farnace and secures a more uniform 
distribution of heat along the whole under surface and 
sides of the shelL 

The walls are" built with air spaces, as shown, to prevent 

radiation of heat. The 
outer wall and the fur- 
nace lining are separately 
laid up, so that the latter 
may be renewed, if neces- 
sary, without disturbing 
the outside walls. 

A transverse section 
of the furnace and side 
walls at the line A in fig- 
ure 107 is shown in fig- 
ure 108. The arch, it will 
be seen, touches the top 
of the boiler and then 
gradually enlarges until 
it has passed the center of 
the boiler, when the sides 
contract to the width of 
the grate. 

Figure 109 represents a transverse section, on the line 
B in figure 107, and is that portion of the furnace known 
as the combustion chamber. The position of grates is 
clearly shown, and attention is directed to the peculiarity 
of their setting. It will be seen that a wall extends from 
the foundation up through the ash pit to a distance of 
about eight inches above the grates, and over this central 
wall is placed a cast iron box, protected by tire brick from 
the intense heat of the furnace. This cast iron box has a 
series of slits along each side of its lower edge. The object 
of this box is to form a receptacle for the heated air forced 




FiGUKE 108. 



THE BUTMAN FURNACE. 



325 



into it by means of the blower, shown on the outside of the 
farnace and marked F. The air is forced out througfh 
these horizontal slits in a thin sheet on each side of the 
center wall and at a distance of tw^o to four inches above 
the surface of the lire. The object of these jets of highly 
heated air in the furnace is to supply the products of com- 
bustion with a fresh supply of oxygen in case it should be 
needed. In the combustion of coal on a grate the air com- 
ing up through the fire from underneath, carbonic acid gas 
is formed as the product of perfect combustion, but in pass- 
ing up through the 
fire the highly heat- 
ed carbon above it 

B 
abstracts from the 




molecule of carbonic 
acid gas an atom of 
oxygen, and two mo- 
lecules of carbonic 
oxide gas are form- 
ed, which renders 
the originally perfect 
combustion incom- 
plete, and thereby 
lowering the temper- 
ature of the furnace 
not only, but allow- 
ing much of the car- 
bon to escape un- 
burned. If,whilethe 
carbonic oxide gas is 
still in the furnace, and at a high temperature, it comes in 
contact with a fresh supply of oxygen, it ignites and is 
again converted into carbonic acid gas, which renders the 
combustion complete, and a great saving in fuel is effected. 



FiGURK 109. 



826 



A TREATISE ON STEAM BOILERS. 



Am. ** > 



The action of the blast, through these side jets, is to 
prevent the localization of an intense heat underneath the 
H boiler at the furnace, and to 

carry it along the sides, and 
distributing it over a greater 
area, and promoting a current 
of hot gases along the sides 
of the boiler instead of confin- 
ing it along the bottom, as is 
generally the case in the ordin- 
ary settings. 

The forcing of the air into 
the cast iron box in the furnace 
is accomplished by means of 
an injector, shown in figure 
110, and is from the designs of 
Messrs. Schutte & Goehring. 

In this jet blower, the in- 
ducing current is a jet of 
steam, the quantity of w^hich 
is controlled by the spindle H, 
in the steam nozzle; the in- 

Lduced current of the air is 
formed in a series of nozzles 
of increasing area. The pur- 
pose of these nozzles is to regu- 
late the admission and proper 
mixture of the inducing and 
induced currents in such pro- 
portions as not to lose power 
by sudden shocks. The quan- 
tity of air to be admitted is regulated by a steam valve, H? 
and is always under the control of the fireman, and may 




DISCHAEGB. 



Figure 110. 



be adjusted as circumstances require. 



THE BUTMAN FURNACE. 



327 




Figure 111. 



Figure 111 is a section at C, showing the compartment 
for heated gas over the 
top of the boiler. The 
line of the pendants, 
already described, is 
shown by the two lines, 
one on either side, and 
just below the water line 
of the boiler. 

Figure 112 shows a 
section at the rear end of 
the boiler, and marked 
D, in figure 107. The 
arch is built down upon 
the boiler at this point, to 
prevent any such thing 
as a current of heated 
gases over the top of the boiler; they are thus carried down 
below the water line, and below the bottom line of pen- 
dants already referred to. 
o The area of openings at 



the sides and above the 
rear bridge wall are pro- 
portioned to the area of 
o]3enings in the flues or 
tubes ; practically, these 
side openings are made 
about one-third greater 
than the combined areas 
of the tubes or flues. 

Figure 113 shows the 
method of utilizing the 
waste heat escaping up 
the chimney. The pipe 
supplying air above the 




Figure 112. 



328 



A TREATISE ON STEAM BOILERS. 



fire starts at the base of the chimney and ascends to near 
the top, thence downward and from the bottom to the jet 
blower, where it is forced into the cast iron box between 
the grates, as shown in figure 109. 

The furnace doors, as usually fitted to this furnace, are 
shown in elevation in figure 114. Unlike the ordinary fire 
door, it is hinged at the top instead of the side. 
The door is slightly more than counterbalanced by 
means of two side weights, shown in the engrav- 
ing. This weight has a segment of a gear cast in- 
side, as shown in figure 115, into which a similar 
toothed segment, fitted to the door, is geared, and 
thus the movements of the door and weight are 
controlled by each other. 

On the same central shaft, around which the 
weight oscillates, is also secured a deflecting plate, 
which is shown in both figures 115 and 116. When 
the door is closed, as shown in figure 115, the de- 
flecting plate is entirely within the 
housing. A butterfly register is at- 
tached to the door, through which 
a greater or less quantity of air 
may be admitted, as it may appear 
to be needed. When the deflect- 
ing plate is down, as shown in 
figure 115, the air passes under- 



FlGURE 113. 



neath its lower edge, and is thus brought, into close sur- 
face contact with the bed of burning fuel. 

. When the furnace door is opened in order to supply 
fresh fuel, the deflecting plate is thrown out horizontally, 
as shown in figure 116 ; the object of this defiecting plate 
being to prevent the cold air from impinging directly 
against the bottom of the boiler, but to so direct its course 
that it shall mingle with the heated gases immediately 



THE BUTMAN FURNACE. 



329 



over the fire, passing otf with them without any local cool- 
ing of the lower part of the boiler shell. 

The grate ased in this boiler setting is quite narrow, 
and, as will be seen in figure 117, one is placed on each side 
of the central wall in the furnace. It belongs to that class 
known as oscillating or rocking grates, and is provided on 



I 




Figure 114. 



its upper surface with oblique cutting edges and interlock- 
ing fingers, which also form parallel cutting edges. 

The cross bar is corrugated in the direction of its length, 
and tapers from the top to its bottom ; the fingers men- 
tioned in the preceding paragraph are attached to it. 
These are '' staggered," as shown in the engraving, so as to 
present a series of irregular orifices, which shall allow a 



830 



A TREATISE ON STEAM BOILERS. 



free and full supply of air to the fuel. These fingers are 
made semi-circular, and when the grate is being " rocked " 
or " shaken/' the same distance is preserved as when in its 

normal condition, thus prevent- 
ing the loss of any small fuel on 
the grate from falling through in- 
to the ash pit. Each grate bar 
has an arm projecting downward, 
as shown ; these pass through 
suitable openings in a connecting 
bar, by which they may all be 
moved at once, which can be done 
without opening the furnace door. 
When the bars are shaken, the 
whole surface of the fuel is broken 
up, allowing at the same time 
complete access of air to the 
burning fuel. 

Rocking grates are to be re- 
commended where the character 
of the fuel will permit, because 
they always prevent in great 
measure, and oftentimes wholly, 
Figure 115. the cloggiug Up of the frcc spaccs 

between the bars. In burning any fuel likely to clinker, 
the spaces are liable to become filled up, and thereby inter- 
fere with the draft. By means of a rocking or oscillating 
grate, the clinkers are prevented from forming, by grind- 
ing or breaking them up as they form. 

The following test of a boiler set with the Butman 
furnace at the flouring mill of G. W. Cunningham, Tifl5.n, 
Ohio, is by Isaac Y. Holmes, M.E., who reports as follows: 

This boiler was set with the Butman furnace and started on the 
first of August, 1876. It has therefore been in constant use over a 
year. On the third of August, 1876, I made an examination and test of 




THE BUTMAN FURNACE. 



331 



the same, a fall report of which was forwarded you at that time. The 
result showed an evaporation at pressure of atmosphere and tempera- 




FlfJURE 116. 



ture of 212° of 11.33 pounds of water per one pound of Masillon lump 
coal. The object you had in view in making this second trial, as stated 




Figure 117. 



to me, was to ascertain if the Butman furnace would retain its econ- 
omic efficiency after being subjected to a year's work, and, also, how 



332 A TREATISE ON STEAM BOILERS. 

the various portions of the structure had withstood the wear and 
burning of the sarne. 

Herewith is submitted a summary of results of the tests made on 
the twentieth instant (August, 1877): 

DU.TY. 

Driving a four-run grist mill Clifton mill 

COAL. 

The kind used on this trial was Masillon nut 

DURATION. 

Continuous firing 7 hours 

OBSERVATIONS. 

Total amount water weighed to boiler ...^ 15,376 lbs. 

Total amount coal weighed to furnace 1,233 lbs. 

Total amount ash weighed dry 87 lbs. 

Total amount combustible 1,136 lbs. 

Average temperature feed water in tank 184° 

Average temperature gases in uptake 340° 

Average temperature air in pipe 132° 

Average temperature air in fire room 97° 

Average pressure steam in boiler 75° 



PERFORMANCE. 

Coal, per hour 176 lbs. 

Combustible, per hour 162 lbs. 

Water, per hour 2,196 lbs 



RESULTS. 



Pounds of water evaporated at 75 pounds 
pressure and temperature of 184° per one 
pound of coal 12.47 

Pounds of water evaporated from pressure of 
atmosphere and temperature of 212° per 
one pound of coal 13.23 

Equivalent evaporation from pressure of at- 
mosphere and temperature of 212° per 
one pound of combustible 14.36 

The evaporation of 13.23 pounds of water at pressure of atmos- 
phere and temperature of 212° shows very conclusively that instead of 
losing its efficiency, it gives a higher rate of evaporation than at first,* 
although this is no doubt due to the familiarity of the fireman with 
the furnace. 



THE PIERCE FURNACE. 



333 



As regards the deterioration of the brick work or other portions of 
the structure will say, there was no perceptible wear to any portion of 
it, and I should not think that even the line of brick at the surface of 
the burning fuel would not require renewing for several years to come. 

The boiler was 60 inches X 18 feet, with fifty-six 3J- 
iiich tubes; was fitted with two grates, as shown in figure 
117, each 15 J inches X 4 feet. The mud drum was 20 
inches X 8 feet. Two things are noticeable in the above 



m ////////////////////M//.^ '''' '■■""'"■'■'■■:■ 




w//////////////////////////////////////////////////////M///m^^^^ 




FlUUKE 118. 



test: the moderately high temperature of the feed water 
and the low temperature of the escaping gases. This is the 
highest rate of evaporation known to the writer, and if it 
were not for the ability and unusual care with which Mr. 
Holmes conducts his tests, the results might be discredited. 



The Pierce furna ce — The accompanying engravings show 
an improved design for boilers' furnaces, by Henry M. 
Pierce, LL.D., of Grand Rapids, Mich. 



334 



A TREATISE ON STEAM BOILERS. 



Figure 118 is a vertical longitudinal section, showing 
the boiler in position in the furnace. In this design the 
fire grate is wholly removed from the boiler and arched 
over, as may be more clearly seen in figure 119. 

The radiant heat of the fuel 
is not given out in this case so 
as to be absorbed by the boiler 
shell, but by the arch of fire brick 
overhead and along the fiue. 
The advantages which such a 
form of construction offers toward 
effecting the complete combustion 
of hydrocarbon gases, when pro- 
perly supplied with air, are too 
apparent to need any special ex- 
planation. 

The furnace is fired in the 
usual manner, the products pass- 
ing over a bridge wall, at a high 
temperature, into a roomy com- 
FiGURE 119. bustion chamber of equal if not 

still higher temperature. In this chamber, jets of heated 
air is admitted through the back of the bridge wall, 
through a perforated plate, as shown in figure 120. This 
supply of air in a chamber, at a temperature of over 1,000° 
Fahrenheit, has the eft'ect to convert the 
volume of carbonic oxide into carbonic 
acid gas. The chamber being large, af- 
fords ample time for complete combus- 
tion ; the passage of the gases through 
it is slow, because of its large area. The 
combustion being complete, the gases pass underneath the 
boiler, and from thence through the tubes to the chimney. 
A furnace, constructed after Dr. Pierce's designs, was 
on exhibition during the Exposition for the year 1879, at 





Figure 120. 



THE PIERCE lURNACB. 



335 



Pittsburo^, Pa., and is 
preferred to the one 
just described, when 
viewed from the wri- 
ter's standpoint. 

Figure 121 is a 
vertical cross sec- 
tion, showing the 
boiler, furnace and 
combustion cham- 
ber. 

Figure 122 is a 
plan of the setting, 
showing the grate ' 
and the combustion 
chamber back and 
along side of the 
grates. The fuel is 
burned upon the 
grate, and, as in the 
heated chamber, say 



in its details of construction, to be 




Figure 121. 



setting first described, in a highly 
2,500° Fahrenheit. Jets of air are 




Figure 122. 

admitted along the sides of the s^rate, as shown in the 



336 



A TREATISE ON STEAM BOILERS. 



engraving. The walls are hollow, as shown by the black 
lines in the plan and elevations, and which serve to heat 
the air before its admission to the combustion chamber. 

This furnace attracted a great deal of attention during 
the exposition. It was fired with Pittsburg coal, which 
was completely burned, and without the escape of any 
smoke. . Suitable openings were made in the combustion 
chamber, which showed that the visible products were 




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Figure 123. 



destroyed immediately after they left the grate. Figure 
123 shows a vertical longitudinal section, with the arched 
opening between the two combustion chambers. 



CHAPTER XIII. 



FEED APPARATUS. 

Power Pumps — Strainers — Removing Sand from Feed Water — Water 
Chargers — Steam Jet — Steam Pumps — Dayton Cam Pump — The 
Cope & Maxwell Pump — Dean Brothers' Pump — The Knowles 
Pump — Auxiliary Pumps — Seller's Injector — Hancock's Inspirator 
— Schutte & Goehring's Injector — Pratt's Automatic Boiler Feeder 
— Snowden's Feed Pipe — Moore's Boiler Feeder. 

Boilers are usually supplied with water by means of a 
pump or injector. Pumps may be divided into two classes ; 
power pumps, or those driven by a belt, and steam pumps, 
or that class in which there is combined a steam cylinder 
and a pump. So long as the machinery is in motion, a 
power pump may be operated at a lower cost than a steam 
pump ; the latter, however, may be operated at any time 
when steam is on, and is, on the whole, to be preferred even 
at its greater first cost and subsequent outlay for oper- 
ating. 

Whatever device may be selected for feeding boilers, 
it should be arranged in matters of detail so as to permit a 
constant feed into the boiler which shall exactly equal the 
evaporation; but this should not be the limit to its 
capacity. 

In selecting a pump, allow one cubic foot of water 
per hour for each horse power of the boiler; the smallest 
size for the pump should be not less than twice that capac- 
ity when running at ordinary speed, and four times the 

(23) 



338 



A TREATISE ON STEAM BOILERS. 



capacity may often be found to be a useful reserve in case 
of ieaky valves, pipes, etc., which are not only liable to 
occur, but at a time when it may not be convenient to take 
the pump apart for repairs. 

When a power pump is used, a combined lift and force 

pump is recom- 
mended ; and, in 
pumping from a 
well, the delivery 
should be into a 
tank of sufficient 
size to supply the 
boiler for at least 
half a day. This 
will, in all ordinary 
cases, allow ample 
time for any small 
repairs that may be 
needed to the lifting 
or well pump. The 
force pump may 
draw the water 
from the tank and 
supply the boilers 
continuously. This 




Figure 124. 



arrangement 



of 
pumps and tank is 
not always practicable, especially for very large powers, 
but whenever it can it ought to be done. 

The engraving, figure 124, shows a very neat and 
compact single acting lift or well pump, by Chandler & 
Taylor, Indianapolis, Ind. It is fitted with leather valves, 
which are conveniently accessible. The piston is packed 
with hemp or jute packing. The counter shaft is fitted 
with tight and loose pulleys, and is thus self contained. 



POAYER PUMPS. 



339 



A boiler feed pump by the same firm is shown in figure 

125. It is similar in design to the well pump, dififering 

only in the plunger and valves. The connecting rod pin 

is near the middle of 

the plunger, and be- 
ing always within the 

bearings of the pump 

barrel and gland, the 

plunger needs no 

other guides. The 

valves are of metal 

and suitable for 

pumping hot water. 

These may both be 

mounted on the same 

base and driven by 

the same belt. 

Pumps should be 

fitted with strainers 

and foot valves; one 

similar to figure 126 

will be found quite 

reliable. It is in- 
tended to screw on 

the lower end of the 

pipe and should be placed near the bottom of the well. If 

a driven well is used 
there is always likely 
to be more or less trou- 
ble with sand in the 
water for some time 
after, in which case a 
device similar to figure 
127, by W. and B. 

Douglas, Middletown, Conn., may be attached to the feed 




Figure 125. 





Figure 126. 



340 



A TREATISE ON STEAM BOILERS. 



pipe and collect a large portion of the sand in the lower 
end of the chamber, from which it may be withdrawn by 

the removal of the plug 




FlUURE 127. 



shown in the engraving. 



Steam jets are often used 
for supplying a tank with 
water either from a well or 
stream, within a reasonable 
distance. A very simple and 
convenient device for raising 
water is shown in figure 128, 
made by Moore & Kerrick, 
Indianapolis, Ind. If the 
well is not deep, it may be 
placed near or above the 
ground, but may be carried 
any distance down the well 
to keep it within the atmos- 
It is so simple as to need no 

special explanation. The quantity of water delivered is 

regulated by the steam valve, which 

may be located at any convenient 

place in the engine or fire room. 

Steam pumps — Notwithstand- 
ing the lower cost at which power 
pumps may be operated, it is still, 
all things considered, in the inter- 
est of true economy to use a steam 
pump instead. The requirements 
of a steam boiler feeder are. 

That it shall have no dead cen- 
ters. 

That it shall be tdmple in con- 
struction and durable in service. figure ris. 



pheric lift of the water. 




DAYTON CAM PUMP. 



341 



That the working parts shall be readily accessible. 

That it will not stop while there is sufficient steam to 
drive it, and if at rest it shall start at any portion of the 
stroke. The water valve chambers must be so constructed 




Figure 129. 



that by simply removing a cover the valves may be 
quickly got at for cleaning or repairs. 

That it shall pump hot or cold water equally well. 

Dayton cam pump — This pump, shown in elevation in 
figure 129, and in section in figure 130, is by Smith, Vaile 
& Co., Dayton, Ohio. 




Figure 130. 



By reference to the horizontal sectional view, it will be 
seen that it is a direct and double acting steam piston 
pump, having a plain slide valve, similar to the ordinary 
D valve of an engine. This valve is moved by two levers, 
A a, on a shaft B, being placed at right angles and form- 



342 



A TREATISE ON STEAM BOILERS. 



ing a bell lever Motion is imparted to these levers by a 
cam C, bolted to the piston rod and working with it, a pin 
on the lever A working in a groove of the cam C ; also, a 
fixed support or pocket, S, which holds a sliding V shaped 
plunger, P, and a spiral steel spring. The operation of the 
valve movement is as follows : The cam, C, near the ter- 
mination of the stroke of the pump piston, brings the Y 
shaped or pointed lever, A, in contact with the Y shaped 




FlGUBK 131. 



plunger, P, forcing it back in the pocket, S, and compress- 
ing the spiral spring contained in the pocket. The move- 
ment of the piston continues until the points have passed, 
when the forcible reaction of the spiral spring, and the 
pressure of the inclined faces of the Y shaped points serve 
to move the lever, A, and, through it and the small lever, a, 
to throw the steam valve, Y, sufficiently to partially open 
the steam port for the return stroke. The same operation 
is performed on the return stroke at its termination, only 
the lever. A, is thrown in the opposite direction. The 
arrangement of the water valves is extremely simple.- The 
pump, being double acting, there are two suction and two 



DAYTON CAM PUMP. 



343 



discharge valves, all contained in one water box on the side 
of the water cylinder. Bv reference to the sectional view 
of water box, a clear idea is obtained of the arrangement 




FlGUUK 132. 




VALVE MOVING SHAFT. 






AUXILIARY VALVK. 




AUXILIARY CYLINDER. 



AUXILIARY VALVE SE AT. 




MAIN STEAM VALVE. 



of the valves, valve seats, stems, springs and plugs, and 
the manner of putting them in. 

This pump possesses, what all pumps should, and that is, 
large steam and water passages. By an inspection of the 



344 



A TREATISE ON STEAM BOILERS. 



details of its moving mechanism, lb will be seen that It can 
never make a short stroke ; each stroke must be completed 
before the steam valve will open, to cause it to make a 
stroke in the opposite direction. 

Figure 131 is a pump fitted with two cylinders, one for 
hot and the other for cold water. This is a step in the 
right direction, and can not fail of appreciation. 




STEAM CHEST AND VALVE SHAFT. 



The Cope ^ Maxwell pump made at Hamilton, Ohio, is 
shown in elevation in figure 132, and is, in this illustration, 
shown as a combined lift and force pump. The details of 
the valve movement will be understood by reference to the 
following description : 

The steam chest, G, is cast in one piece with the steam 
cylinder head, and has neither bolt, nut, screw or joint of 
any kind, inside of it or about it, except its cap or cover. 
On removing the cap the entire valve movement can be 
lifted out, or any part of it removed and another substi- 
tuted, ready for instant operation, without requiring to be 
fitted and without breaking or making a single joint, con- 
nection or attachment. There are no ports passing through 
gasket joints; no long crooked or small ports or holes to 



COPE & MAXWELL PUMP. 345 

get stopped up with dirt; no pockets to retain water and 
incur risk of damage from frost, and no point about it 
requiring adjustment. 

. The main steam valve, A, is a flat slide valve, and is 
cast in one piece with the auxiliary pistons, B B, and the 
seat, C, of the auxiliary steam valve, E, as shown in 
engraving. It is moved continuously through the first 
half of its travels by the power of the main piston, and 
through the last half by the power of the auxiliary pistons, 
B B. 

The auxiliary steam valve, B, is also a flat slide valve, 
and moved continuously by the power of the main piston. 

The auxiliary steam cylinders, H H', are composed of 
two plain hoods or caps, each locking in to a central con- 
necting piece, D, which holds them in position. They are 
put together or taken apart without the use of tools. It 
simply requires to be set down in its place in the steam 
chest, without further attention, to keep it in place. Being 
located in the steam chest, it is constantly surrounded by 
live steam, securing the best possible steam jacket without 
special provision. 

The valve moving shaft, F, is a plain shaft extending 
through the back wall of the steam chest, connected on 
the outside to the main piston rod by means of lever and 
connecting rod, and terminating on the inside in a collar 
provided with two lugs, the lower one locking into the cen- 
tral or connecting piece of the auxiliary steam cylinders, 
H H', so they shall move together, and the upper, locking 
into a recess in the back of auxiliary steam valve so as to 
give the desired motion to it. 

Operation — The reciprocating motion of the main piston 
communicates a rocking motion to the valve moving shaft, 
F, which, by means of its connection with the auxiliary 
steam cylinder, moves it back and forth. The main steam 




Figure 133. 



DEAN BROTHERS PUMP. 



347 



valve, A, being cast in one piece with the pistons of the 
auxiliary cylinder, is moved with the cylinder, and it is so 
arranged that the main piston in making its full stroke 
causes the main steam valve. A, to move from its end to its 
mid position, cutting off both steam supply and exhaust 
in time to arrest the motion of the piston at the desired 
point, thus giving almost absolute uniformity to the length 
of strokes and furnishing it a very superior cushion. 




Figure 134. 



Just before the main steam valve reaches its mid posi- 
tion, the auxiliary steam valve, E, moved by means of its 
connection with the valve moving shaft, F, reaches the 
proper position for giving steam to the auxiliary cylinder 
and motion to its piston. The main steam valve being one 
piece with this piston is thus carried from its mid position 
to the end of its travel, reversing the steam and its exhaust 
ports and the motion of the main piston. 

Figure 133 shows the pump, as arranged for deep well 
pumping. The lower or lifting pump may be at any depth 
below the surface of the ground. The connection between 



348 



A TREATISE ON STEAM BOILERS. 



the lower chamber and the base of the pump is ordinary 
iron pipe, the lifting rod passing up through the center, as 
shown. 

Dean Brothers' pump-^This pump is shown in elevation 
in figure 134, in which a vertical longitudinal section of the 
water cylinder is also shown, with the valves in place. 
Figure 135 is a plan of the pump, showing the steam valve 
and ports, and the opening at the side of the water cylinder 
for the water supply. 




Figure 135. 

It is a simple slide valve engine, combined, in a novel 
and compact manner, with the best form of a double act- 
ing pump. Care has been taken that the parts can be 
readily examined or removed, and all parts subject to wear 
have means of adjustment. It has but one steam valve. 
This is a fiat slide valve, which embodies the most favorable 
conditions for tightness even after the wear consequent 
upon a long use. It is provided with a fiy wheel, which 
causes it to run without concussion or jar, turns the centers 
softly and allows the water valves to seat quietly. The 
stroke is always the same. This wears the cylinders per- 
fectly true, and discharges the full amount of water against 
the heaviest pressure. 

The Knowles 'pumjp—Thi^ pump is shown in vertical 
longitudinal section in figure 136. Mr. L. J. Knowles, 



THE KNOWLES PUMP. 



34^ 







350 



A TREATISE ON STEAM BOILERS. 



Warren, Mass., was probably the first to introduce the direct 
acting, positive motion steam pump in this country. This 
pump has had a very large sale, and has proven a great 
success. The steam valve is a common flat slide valve, 
actuated by means of the valve driving piston, both of 

which are shown in detail in 
the engraving. The steam 
valve of the pump being an 
ordinary flat slide valve, does 
not have a rotary motion, but 
simply a horizontal motion, 
the same as any slide valve. 
A flat valve embodies the 
most favorable conditions for 
securing tightness in the pro- 
cess of manufacture and re- 
taining it in constant service. 
The slight rotary motion im- 
parted to the valve driving 
piston, by the rocker arm, 
simply puts it in a position 
to be driven horizontally by 
the steam, in which motion 
it carries the slide valve with it, both being directly con- 
nected together. 

The driving piston is entirely independent of the 
exhaust- steam for cushioning, thereby working with the 
same certainty and exactness when exhausting into vacuum 
(working condensing) as when exhausting into the atmos- 
phere. It will always start at any point of the stroke, and 
recent improvements applied to the pump insure entire 
freedom from jar or pounding under varying conditions of 
pressure. 

Auxiliary pumps — In every large manufactory, or in any 
case where the quantity of water required is too great to 




Figure 137. 



AUXILIARY PUMPS, 



351 




Figure 138, 



352 A TREATISE ON STEAM BOILERS. 

have storage in suitable tanks, there should be an independ- 
ent source of water supply for use at such times as the 
steam may not be on the main boilers. This will be found 
useful in washing out the main boilers during the process 
of cleaning. It may also serve a useful purpose as a fire 
engine, by starting a fire in the boilers about quitting time 
and place it in the care of the watchman during the night, 
and thus be ready for service at any moment. Figure 138 
shows such a boiler and pump as made by the Knowles 
Steam Pump Works. 

Should there be a difficulty in starting the pump on 
account of any defect in the suction pipe, a "charger," as 
shown in figure 137, may be employed. This should be of 
sufficient size to charge the water cylinder and fill the ports 
at least twice, after which there will be no trouble. 

Injectors — This very ingenious and useful device for sup- 
plying boilers with water was invented by M. Giffard, of 
France. It was an innovation on old methods, and at- 
tracted the attention of engineers everywhere. Among 
the first to appreciate the value of this invention was the 
firm of William Sellers & Co., Philadelphia, Pa., who in- 
vestigated its action, satisfied themselves as to its entire 
practicability, and at once received the right to manu- 
facture. It was a fortunate circumstance, indeed, that 
this instrument, almost unknown and wholly untried in 
this country, had as its sponsor a firm whose reputation 
was already well established and who not only gave it 
their fullest endorsement, but labored diligently to improve 
it. The earlier instruments were in many respects faulty 
in their practical workings, but by successive changes and 
improvements, added year by year, the old injector has 
almost entirely lost its identity in the new. The principle, 
however, remains the same. 



SELLER S INJECTOR. 



353 



The Seller's injector is shown in elevation in figure 139, 
and represents the latest improved form. It is known as the 
^' Self- Adjusting 1876 Injector/' and will be best explained 
by reference to figure 140, which is a sectional view of the 




Figure 139. 



same instrument. It will be observed that it is self con- 
tained; that is, there is contained within the instrument 
itself the necessary steam and check valves required in its 
ordinary service. 

The injector is operated by a single movement of the 
lever H, and its action may be traced through the instru- 
ment as follows : The steam, water, and boiler connections 
are indicated in the sectional view, and need no further 
description. By the movement of the lever H, the cross- 
head I slides on the guide-rod J, and thus communicates 
motion to the rod B, which passes through the stufi&ngbox 
into the interior. A valve W, is secured to the rod B, and 
(24) 



i 



354 



A TREATISE ON STEAM BOILERS. 



has its seat on the upper side of another valve, X. The 
receiving tube A, contains both of these valves, and the 
passage of steam through this tube is prevented or con- 
trolled by the valve X. By a close examination of the 




FiGUKE 140. 



engraving, there v^ill be seen a hollow spindle beginning 
at W and terminating at C. This spindle passes through 
the valve X, and may be moved independently of it for a 
short distance, but by a further movement of the lever H, 
the valve X is raised fi'om its seat by means of a stop 
attached to the hollow spindle, formed by an enlargement 
of the spindle a short distance back of the valve X. Thus 
the first movement of the lever is to admit steam to the 
center of the spindle, by the unseating of the valve Wand 
without disturbing the valve X. It will be understood that 
what has just been described belongs to the steam side of 
the injector. 



SELLER S INJECTOR. 355 



The water enters, as indicated by the arrow, into the 
chamber surrounded by the cylinder marked M M. Inside 
of this cylinder is a piston ]^ I^, which terminates in 
a gradually contracting nozzle at a point just beyond 
C 0. This piston is fitted to slide in the cylinder M M. 
By a slight movement of the handle H, a jet of steam will 
issue from the central hole in the spindle and a partial 
vacuum will be formed in JN" 1^ ; the water will be drawn 
into this tube, and forced through the delivery tube D. 
When sufficient water has passed through the instrument 
to flow "solid" out of the waste-orifice P, then the lever 
H may be drawn out to its full extent. By this single 
movement, the valve E, is closed by means of the rod L, 
and the valve X opened, which will result in a continuous 
flow of water past the check valve into the boiler. 

The rod L, shown in connection with the valve R and 
the lever H, is fitted with two stops, shown at T and Q. 
When the lever is thrown forward, as shown in the engrav- 
ing, the valve R is raised from its seat by the screw shown 
at its lower extremity. When the lever is pulled back, so 
as to fully open the valve X, the valve R will be closed by 
the action of the stop T on the rod L. The lever H may 
now be moved at any point between the stops T and Q 
without affecting the waste valve ; and b^ the movement 
of this lever the amount of water to be delivered is regu- 
lated. 

The guide rod J is fitted with a number of teeth, as 
shown. A small click shown at V is hinged to the lever H, 
and is free to drop into the notches between the teeth in J. 
When the proper adjustment has been made by the lever 
H, for the water delivery, the click engages the space below 
and the injector will continue to deliver a quantity of water 
corresponding to the area of opening and pressure of steam. 

The steam supply must be adjusted by the operator; 
the water supply is self regulating. If too much water is 



356 A TREATISE ON STEAM BOILERS. 

delivered, some of it will escape through O into C, and, 
pressing on the piston JST 'N, will move the combining tube 
away from the delivery tube, thus throttling the water 
supply; and if sufficient water is not admitted, a partial 
vacuum will be formed in C, and the unbalanced pressure 
on the upper side of the piston l!^ E" will move the com- 
bining tube toward the delivery tube, thus enlarging the 
orifice for the admission of water. From this it is evident 
that the injector, once started, will continue to work with- 
out further adjustment, delivering all its water to the 
boiler, the waste valve being kept shut. By placing the 
hand on the starting lever it is easy to tell whether or not the 
injector is working; and if desired, the waste- valve can 
be opened momentarily by pushing the rod L, a knob on 
the end being provided for the purpose. 

These injectors are made in several sizes and numbered 
2, 3, 4, etc. These are not arbitrary numbers but repre- 
sent the diameter of the smallest part of the delivery-tube 
expressed in millimeters. Thus a N^o. 5 injector means 
that the tube through which the water is driven in passing 
thr„ough the delivery tube, is ^ve millimeters in diameter. 
A 1^0. 8 injector has a tube eight millimeters in diameter; 
and so for each of the sizes. 

The non- adjustable injector with fixed nozzle^ non-lifting^ is 
shown in elevation in figure 141, and in section in figure 
142. The latter figure, it will be observed, is reversed in 
the engraving, but will be none the less easily understood. 

This injector differs from the one already described in 
being non-adjustable, and having no valve attached to it. 
The interior arrangement will be comprehended at a glance, 
after reading the description of the self adjusting instru- 
ment. This injector is best suited to localities where it may 
be operated under practically constant conditions — that is, 
where the steam pressure is nearly constant at all times. 



seller's injector. 



357 



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358 



A TREATISE ON STEAM BOILERS. 




Figure 141. 



It will be observed that it has neither steam nor 
check valves ; these may be supplied by the ordinary steam 

fittings. Unlike the 
former injector, it is 
necessary to have a 
valve in the water 
pipe in order to reg- 
ulate the supply, be- 
cause the flow of 
water into this in- 
jector must be regu- 
lated with reference 
to the steam supply 
on account of the 
nozzles being fixed, 
and in consequence, 
not self adjusting. If not supplied with the proper 
amount of water for the steam pressure under which it is 
working, it will leak at the waste valve when the water 
supply is too great. 
To operate this 
injector, it is neces- 
sary to open the 
water supply valve 
first, the waste valve 
being open mean- 
while, and when the 
water flows from the 
waste valve, partial- 
ly open the steam 
valve until the jet 
is established, then 
quickly open it to 
its full extent. As the ordinary screw stop valve can not 
be easily or quickly handled, a special valve is made for 




Figure 142. 



seller's mJECTOR. 



359 



the purpose. The waste valve may be closed or not, but 
if the steam pressure is not constant it is best to leave it 

open. 

This is not a lifting injector, and in consequence the 
water must be supplied to it so that it shall flow into the 
instrument, or be fed to it at any pressure, as for city mains. 
A modification of this instrument, with a lifting attachment, 
is shown in figure 143. 




Figure 143. 



The non-adjustable injector, with fixed nozzles, in connection 
with a lifting attachment, is shown in elevation in figure 143. 
This is a much more complete instrument than the one 
described in the preceding section, and in some respects is 
to be preferred to it. By referring to figure, 144 which 
shows the interior of this injector, there will be seen 
attached to the under side another and independent series 
of passages, arranged with a suitable nozzle to act as a 
steam jet or siphon. 

By this arrangement water may be drawn from a lower 
level up and into the water chamber and through the 



360 



A TREATISE ON STEAM BOILERS. 



combining tube ready for the action of the main jet of the 
injector by the opening of the lower valve. When the jet 
is established the lower valve must be closed. 

This injector, unlike the former, has a steam valve and 
check valve contained within it. In connecting this injec- 
tor it must be provided with a water supply valve, for the 
reason that the nozzles are non-adjusting. 




Figure 144. 



Selectioyi of an injector— 0^ the three instruments 
described the writer recommends the first as being best 
adapted for ordinary service. 

To determine the size of injector needed for any par- 
ticular case, a knowledge of the number of cubic feet 
of water required per hour will enable an injector to be 
selected, by referring to the table of capacities as given on 
page 357. The makers of this injector recommend that 
the one selected shall in no case be larger than is needed 
for the actual maximum requirement of the boiler. If too 
large an instrument be selected, the minimum delivery of 
water may be too great for the wants of the boiler, requir- 



THE HANCOCK INSPIRATOR. 



361 



ing frequent stoppage to prevent flooding, which, apart 
from the trouble involved, is not so economical as a con- 
stant and regular feed equal to the drain on the boiler. For 
stationary boilers, where the work is nearly constant, the 
selecting of an injector is not attended with any special 
difficulty. Knowing the horse power required of the boiler, 
allow one cubic foot of water per 
hour per horse power for ordin- 
ary slide valve engines, and one 
half a cubic foot for the best au- 
tomatic cut off engines, and the 
matter of selection by the aid of 
the table on page 357, becomes 
exceedingly simple. 

The Hancock inspirator — This 

instrument is the invention of 

John T. Hancock, Suffolk, Mass. 

. . . ' 

and differs from an injector in 

being a double instrument, one- 
half of which is a lifting and the 
other half a forcing apparatus; the lifter drawing the 
water from a well or tank and delivering it to the forcer, 
which then delivers it to the boiler, and at any steam 
pressure, without adjustment. 

Two forms of inspirators are made; the one illus- 
trated in figure 145 is a sectional view of the kind recom- 
mended for stationary boilers. The steam connection with 
the boiler is made at the end so marked in the engraving, 
and its course through the instrument is shown in the 
direction of the arrows. That side of the instrument at A 
is known as the lifting side, the other, B, C,D, as the forc- 
ing side. It will be observed that the steam current is divided 
in the upper chamber ; a portion of the steam passing down 
through the vertical nozzle operates the steam lifting noz- 




wateb feed 

Figure 145. 



362 A TREATISE ON STEAM BOILERS. 

zle at A, the water ascending around and passing down 
through the lower tube as shown, into a chamber, where 
it is delivered as also shown by the direction of the arrows 
into the nozzle opposite D, on the forcing side of the instru- 
ment. By raising the valve at B, steam is admitted through 
the nozzle at C, which acts as a forcing jet, compelling a 
'flow of water through the force nozzle, D, and from thence 
to the boiler. 

A valve is provided at E which determines the course 
the water is to take when delivered into the water chamber 
by the action of the lifting jet. This is to be opened when 
starting the instrument, and closed as soon as the action of 
the jet is established. 

To regulate the delivery to the boiler it is only neces- 
sary to partially close the valve in the pipe leading from 
the inspirator to the well, and by also adjusting the steam 
valve by the handle at B. The usual steam, water and 
check valves are to be supplied. 

The essential conditions to the successful operating of 
the inspirator, are, 

1. A tight suction ; the inspirator raises the water 
by causing a vacuum; of course, this can not be obtained 
without having the suction pipe and connections absolutely 
air tight. 

2. Do not connect with other steam pipes, but take 
the steam direct by tapping the boiler ; because, wheie 
steam pipes are already connected with the boiler, it is 
for some purpose, and they are not likely to be of suf- 
cient capacity to supply the inspirator, and do the work 
for which they were originally designed. Again, the 
connection may be at a considerable distance from the 
boiler, so that the steam in the pipe is much reduced 
in pressure, and not so effective for the purpose as 
dry steam. Do not connect with a steam pipe, however 



THE HANCOCK INSPIRATOR. 



363 



large, that supplies the engine, if it can possibly be 
avoided, as the pressure will be so irregular and intermit- 
tent as to seriously interfere with the successful working 
of the inspirator. Tap the boiler where it will furnish the 
dry est steam, and if compelled to connect with a large 
steam pipe, tap it on the upper side, so as to avoid the 
drip caused by condensation in the large pipe, or the steam 
pipe will be little else than a drain to draw off the con- 
densation in the large pipe. 

Do not attempt to take water at a higher temperature 
than 120° Fahrenheit for a low lift, or higher than 
100° Fahrenheit for a high lift. For a lift of 5 feet, 
about 10 pounds steam pressure is required ; for 10 feet lift 
about 15 pounds steam ; for 15 feet, 20 pounds; for 20 feet, 
25 pounds ; for 25 feet, 35 pounds. 

The following are the sizes and capacities of inspirators 
offered to the trade : 



TABLE LXXXX. 

SIZE OF CONNECTIONS FOR THE HANCOCK INSPIRATOR. 



NO. OF 
INSPIRATOR. 


SUCTION AND FEED. 


STEAM. 


GALLONS PER HOUR, 
60 LBS. PRESSURE. 


n 


4 


1 


60 


10 


1 


3 

8 


120 


m 


~ i ' 


i 


220 


15 


3. 
4 


1 


300 


20 


1 


f 


540 


25 


n- 


1 


900 


30 


n 


H 


1,260 


35 


n 


n 


1.740 


40 


2 


n 


2,230 


45 


2 


n 


2,820 


50 


2i 


2 


3,480 



564 



A TREATISE ON STP]AM BOILERS. 



When the consumption of fuel is known, the pounds 
of coal consumed per hour will be the gallons evaporated 
per hour. When the grate surface is known, and the 
draft is natural, multiply the grate surface in square feet 
by 9, and when the draft is forced, add 50 per cent for the 
gallons evaporated per hour. 

A special form of inspirator is made for locomotive use, 
and shown in elevation in figure 146, and in section in 
figure 147. 




tVEBfUW 

Figure 146. 




Figure 147. 



The principle of action is the same for both designs; 
the locomotive inspirator has such an arrangement of 
parts and operated by suitable connections that, the start- 
ing, stopping or the regulating of the instrument while 
working, is controlled by the action of a single lever. 
It also contains the necessary steam, check and overflow 
valves. A slight movement of the starting lever admits 
steam to the lifting jet. When water issues from the over- 
flow, a further movement of the starting lever closes one 
of the valves, thus turning the supply water through the 
force nozzle, admits steam to the forcing jet and closes the 
waste valve, thus starting the instrument. 



SCHUTTE & GOEHRING S INJECTOR. 



365- 



Schutte ^ Goehring's universal ivjector — This instrument 
is shown in sectional elevation in figure 148. 

As will be observed, the instrument is a combination of 
two steam jet apparatus; the first one is proportioned for 
lifting and delivering the water under some pressure into 
the second one where its velocity is sufficiently augmented 
to overcome the counter pressure of the boiler. The 




STEAM 



WATER 



t 



Figure 148. 



explanation of the proper working of the injector, at the 
lowest as well as the highest steam pressures, without any 
adjustment of parts, is formed in the fact that the quantity 
of the water taken in by the first apparatus and delivered 
to the second one is directly in proportion to the pressure 
of the steam, so that the first one acts as a governor for the 
second one. 

This combination of the two apparatus, and its self 
governing qualities without moving parts, makes the 
apparatus the least sensitive, a great desideratum on loco- 
motives. 

The limits of admissible temperature are, feed water 
150° Fahrenheit delivered into the boiler, with 150 pounds 
steam at 250° Fahrenheit. 



4 



366 



A TREATISE ON STEAM BOILERS. 



The injector may be fixed horizontal or vertical. There 
should be a steam stop valve and a main check valve on 
boiler. If water flows to the injector it is necessary to 
have a stop valve in the water pipe; it is also recommended 
in all cases to have such a valve for regulating the capacity 
of the injector. 

If the injector has to draw the water, open the handle 
A, half way, or until the water is discharged through the 
starting cock, then open full. This stop need be of so short 
duration that a continuous moderately slow movement will 
accomplish the required result, so that the instructions for 
manipulation would read: To start, open with handle A. 
To stop, shut with handle A. 

TABLE LXXXXI. 

CAPACITIES OF SCHUTTE & GOEHRING'S INJECTOR. 





SIZE OF 
CON- 


SIZE, 


NO. 


NEC- 




TION. 


2 


i 


3 


1 


4 


1 


5 


n 


6 


n 


7 


n 


8 


n 


9 


2 


10 


2 


12 


2} 



PRESSURE OF STEAM, IN POUNDS. 



15 30 45 60 80 



100 



120 



140 



160 



CUBIC FEET OF WATER PER HOUR, OR HORSE POWER OF BOILER. 



18 

41 

75 

110 

160 
248 
300 
375 
460 
710 



8 


9 


10 


11 


12 


14 


15 


16 


18 


20 


22 


24 


28 


31 


34 


37 


35 


40 


45 


50 


55 


60 


65 


70 


52 


58 


66 


73 


80 


87 


94 


103 


80 


90 


100 


110 


120 


130 


140 


150 


104 


122 


140 


158 


176 


194 


212 


230 


140 


160 


180 


200 


220 


240 


260 


280 


175 


200 


225 


250 


275 


300 


325 


350 


220 


250 


280 


310 


340 


370 


400 


430 


310 


360 


410 


460 


510 


560 


610 


660 



HEATER AND BOILER FEEDER. 



367 



A combined feed water heater and boiler feeder, as manu- 
factured by the Steam^ Boiler Appliance Company, Hart- 
ford, Conn., is shown in figure 149, in general elevation, 
with the several attachments, all made to illustrate its mode 
of operation. 




FiGUKE 149. 



A is the body of the heater and feeder, inside of which 
is a tight, hollow cast iron sphere, suspended on one end of 
a lever, the other end of which is fast to a spindle, run- 
ning through a stuffing box to the outside,^and carrying 
on its outer end lever B, with the weight which counter- 
poises half or more of the weight of the sphere inside the 
heater. is a rocking lever, carrying a grooved weight, 



368 A TREATISE ON STEAM BOILERS. 

which rolls to either end of lever C alternately as the 
heater is tilled and emptied, the rolling weight moving at 
the same point every time, tripping the steam valve D open 
and shut. E is a connecting rod between valve D and 
rocking lever C. F is the feed pipe to boiler. His a steam 
pipe from the boiler to valve D ; this pipe must come direct 
from steam space of boilers. J is an air or vent cock. K 
is a check valve on air pipe, opening outward. L are check 
valves on exhaust, water inlet and outlet pipes. 

In the cut the steam valve D is closed, and the water 
entering the heater causes a partial vacuum, so that all the 
exhaust steam that the water will absorb is drawn into it, 
heating the water to the highest temperature attainable 
by use of exhaust steam without back pressure on the 
engine. As the heater fills with water, the iron sphere or 
bucket inside is raised by it, and lever B goes down until 
it has elevated the inner end of rocking lever C sufficiently 
to cause the grooved weight to roll to the outer end, open- 
ing the steam valve D and allowing the boiler pressure to 
be thrown instantly on top of the water in the heater, and 
seating the check valves on water and exhaust pipes so 
that steam from the boiler can not pass into them; the 
water is now quickly discharged into the boilers by its own 
gravity, and as the water runs out of heater lever B goes 
up until the grooved weight rolls inward and closes the 
steam valve. 

The cold water enters the heater in different ways, 
according to the amount of its pressure. Where it is 
heavy a positive valve is put on for it to run through ; there- 
fore it is necessary to know the amount of pressure in boil- 
ers, the amount of cold water pressure, size of engine 
(H. P.), size of exhaust pipe from engine, what portion of 
the steam made in boilers is used by the engine, size of 
feed pipes to boilers, and elevation the heater can be set 
above the boilers. As the capacity of the heater and feeder 



AUTOMATIC BOILER FEEDER. 



369 



depends very much upon the circamstances under which 
it is used, it is necessary to have all these particulars in 
order to adapt the apparatus to the work to be done. 

By means of suitable connections this same apparatus 
may be used as an automatic holler feeder and return steam 




Figure 150. 



trajp, and may be used for supplying boilers with water 
from all sources where there is pressure enough to lift it 
above the boiler, such as hydrants or tanks, and also con- 
densation from steam heating or drying pipes, drying 
cylinders, boiling pans, main steam pipes to engines, or 
wherever condensation occurs under pressure, whether 
above or below the boilers. 
(25) 



370 A TREATISE ON STEAM BOILERS. 

The apparatus with the connections is shown in eleva- 
tion in figure 150. Similar letters of reference in this 
engraving refer to similar parts as descrihed in figure 149. 

The small valve shown on the trap, connected to steam 
valve D, is used where the water pressure is sufl3.cient to 
run into the holler against the pressure in it, if returning 
from high pressure circulations, etc., or if returning from 
low pressure dryers, slashers, etc., if the water pressure is 
above that used in them. The water going through this 
valve can come through a heater where an engine is used. 
The feeders should be set from two to six feet above the 
water line of boilers ; the higher, the quicker the discharge. 

Admission of feed water into the boiler — The usual prac- 
tice is to supply boilers with the feed as far from the fur- 
nace as possible, and near the bottom of the boiler. It 
may be questioned whether this is the best thing to do. 
If the water entered the boiler at or near the boiling point, 
it would make but little difference where the feed pipe 
made its connection, so long as the delivery was at a dis- 
tance of several inches from the bottom of the shell, if it 
is an externally fired boiler. 

As to the amount of injury done a boiler, a great deal 
will depend as to whether the feed water impinges against 
highly heated plates, and whether a good circulation is 
had in the boiler. The tendency of the cold water entering 
at the back of the boiler is to descend and traverse along 
the bottom of the shell toward the front end, that being 
the direction of the circulation of water. During this 
time there is a difi:usion of heat, in which the feed is con- 
stantly receiving increments of heat from the surrounding 
and intermingled particles already more highly heated, 
and which are moving in the same direction. Just what 
distance the feed has to traverse in this current before it 
becomes harmless when it comes in contact with the 



SNOWDEN S FEED PIPE. 



371 



plates, the writer does not know, and he is not aware of 
any experimental data relating to it. 

Boilers commence leaking water by the rivet holes 
becoming elongated by the strain produced by contraction, 
and they often break out and are required to be replaced 
by new sheets. This is not only troublesome to engineers, 
and expensive to owners, but it is a source of great danger 
also, as no doubt many disastrous explosions have occurred 




Figure 151. 



from this cause. Figure 151 is a representation of a device 
for feeding boilers, by Thomas Snowden, Pittsburg, Pa. 

The nature of the improvement consists in locating a 
feed water pipe within the boiler, having one end of the 
pipe communicating with the feed pump, by being attached 
to the check valve,"c. The pipe is then carried through 
the shell of the boiler and connected with a horizontal 
pipe running along the boiler above the water line, to near 
the opposite end, after which it returns to the end at which 
it entered, and turning down to the stand pipe, dis- 



872 



A TREATISE ON STEAM BOILERS. 



charges into the water space of the same. The check 
valve may be if necessary, placed below, the supply pipe 
entering the boiler through the stand pipe and running 
.up to the horizontal pipe. By this means the feed 
water is heated within the boiler, in its passage through 
the pipe, before it empties into the water space; thus 
the destructive consequences which result from introduc- 




FlGURli 152. 



ing water of a lower temperature than the boiler plate is 
prevented. 

Moore's boiler feeder aud cleaner is represented in figure 
152, and is the invention of Mr. George W. Moore, Pitts- 
burg, Pa. The object of introducing the feed into the 
steam room of the boiler is to impart to the water 
a high temperature before it comes in contact with the 
boiler plates. 



moore's boiler feeder. 373 

The water is admitted through the shell of the boiler 
and discharges upwards through the check valve, as shown 
The feed water, falling on the surface of the water in the 
boiler, mingles with it, and it is claimed with less injury to 
the shell than by any other method. It is equally applica- 
ble for hot or cold water and will work with any device 
used for forcing water into the boiler. It is claimed that 
the first eflect of this heater is to detach or loosen the old 
scale in the boiler, and it has been found necessary to wash 
out and examine the boiler after applying the heater. 

The boiler should not be run more than three weeks 
without washing out, and as the boiler becomes cleaner, 
the running time may be extended to one month, and 
when the boiler becomes clean and free from scale, all 
that will be necessary to keep it clean will be to blow 
out at the mud valve two or three times a day. By 
the observance of this rule, there will be no danger of 
burning a boiler, which would be the result if the loose 
scale was not removed. 



I 



CHAPTER XIV. 



HEATERS AND ECONOMIZERS. 

Gain by the use of Heaters — Coil Heaters — Stillwell's Lime Extractor 
and Heater — Green's Heater — Victor Heater — Kemp's Boiler 
Cleaner — Stead's " Circulating Generator " — Economizers — Bab- 
cock & Wilcox Economizers — Johns' Asbestos Covering — Cham- 
feers-Spence Covering. 

The advantages to be gained by heating feed water to 
as high a temperature as possible before allowing it to enter 
the boiler, is so apparent that it need not be enlarged upon. 

This gain, however, should be entirely that of reclaim- 
ing from the waste gases from the furnace or from the 
exhaust steam, heat which would otherwise be lost. 

In order to illustrate this saving, let us suppose a 
boiler to be carrying steam at 60 pournd pressure per 
square inch, as indicated by the gauge, the temperature of 
the feed water being at 60° Fahrenheit. 

By referring to table LIX, on page 205, we find the 
total heat required to generate one pound of steam at 60 
pounds pressure from water at 32° Fahrenheit to be 1175.2 
heat units. This represents the quantity of heat abstracted 
from the furnace to generate one pound of steam at 60 
pounds pressure, the feed being 32° Fahrenheit ; if, how- 
ever, the feed be 60°, as already suggested, then each 
pound of steam would abstract from the furnace 1147.2 
heat units. If the temperature were 200°, then 200 — 
32 = 168°, which, subtracted from 1175.2 = 1007.2 heat 
units, and in this manner for other temperatures. 



COIL HEATERS. 



375 



TABLE LXXXXII. 

PERCENTAGE OF SAVING OF FUEL BY HEATING FEED WATER.=:= 
(Steam at Sixty Pounds). 



FINAL 
TEM- 


INITIAL TEMPERATURE OF WATER. 


PERA- 
TURE. 


32° 


40° 


50° 


60° 


70° 


80° 


90° 


100° 


120° 


140° 


160° 


180° 


200° 


60° 


2.39 

4.09 

5.79 

7.50 

9.20 

10.90 

12.60 

14.30 


1.71 

3.43 

5.14 

6.85 

8.57 

10.28 

12.00 

13.71 


0.86 
2.59 
4.32 
6.05 
7.77 
9.50 
11.23 
13.00 














1 






80° 


1.75 
3.49 
5.23 
6 97 
8.72 
10.46 
12.20 


0.88 
2.64 
4.40 
6.15 
7.91 
9.68 
11.43 










1 






100° 


1.78 
3.55 
5.32 
7.09 
8.87 
10.65 


0.90 
2.68 
4.49 
6.26 
8.06 
9.85 






1 






120° 


1.80 
3.61 
5.42 
7.23 
9.03 












140° 


1.84 
3.67 
5.52 
7.36 










160° 


1.87 
3.75 
5.62 








180° 


1.91 
3.82 






200° 


1.96 




220° 


16.00 


15.42 


14.70 


14.00 


13.19 


12.33 


11.64 


10.84 


9.20 


7.50 


5.73 


3.93 


1.98 


240° 


17.79 


17.13 


16.42 


15.69 


14.96 


14 20 


13.43 


12 65 


11.05 


9.37 


7.64 


5.90 


3.97 


260° 


19.40 


18.85 


18.15 


17.44 


16.71 


15.97 


15.22 


14.45 


11.88 


11.24 


9.50 


7.86 


5.96 


280° 


21.10 


20.56 


19.87 


19.18 


18.47 


17.75 


17.01 


16.26 


14.72 


13.02 


11.46 


9.73 


7.94 


300° 


22.88 


22.27 


21.61 


20.92 


20.23 


19.52 


18.81 


18.07 


16.49 


14.99 


13.37 


11.70 


9.93 



Coil heaters — The commonest form of a feed water heater 
is a large pipe, usually of cast iron, containing a number 
of smaller wrought iron pipes, which traverse the length 
of the interior several times, the feed water passing through 
the inside of the smaller pipes, and the exhaust steam from 
the engine filling the larger shell. In this manner a con- 
siderable saving is effected; the amount may be deter- 
mined by the use of the above table. As no further use is 
usually made of the exhaust steam after leaving the 
engine, any heat which may be abstracted by the feed water 
in this way is nearly all clear gain. 

- From " steam," by Babcock & "Wilcox, N. Y, 



376 



A TREATISE ON STEAM BOILERS. 



StillweWs lime extracting heater and filter combined, as 
manufactured by the Stillwell & Bierce Manufacturing 

Company, Dayton, O., 
is shown in sectional 
elevation in figure 153. 
The details of its con- 
struction will be easily 
understood by reference 
to the following letters 
contained in the en- 
graving, the several 
functions of the parts 
referred to being as 
given below : 

A — Steam enters the 
heater, and is divided 
into two currents. B 
— Steam escapes from 
the heater. C — Cold 
water enters. F — Cock 
with which to regulate 
supply of cold water. 
H — Door of heater. J 
— Hot w^ater leaves 
heater. L— Glass water 
gauge. a — Overflow 
cup suspended on the 
end of cold water pipe, 
b b b b — Removable 
shelves or depositing 
FiGUKtii53. surfaces, c — Filtering 

chamber to be filled with any suitable filtering material. 
The feathered arrows indicate the course of the steam, 
and the plain arrows the course of the water. 




stilwell's lime-extracting heater. 377 

Its operation is as follows : Connection is made at A 
with the escape pipe from the engine, where the steam is 
divided and enters the heater at two ports, one just above 
the upper shelf, the other opposite the lower shelf. The 
outlet pipe, B, for the escape from the heater of the uncon- 
densed steam, is of the same size as the inlet pipe A. The 
escape steam from the heater may be carried to any desired 
point and applied to any further use, such as heating 
rooms, steaming lumber, etc. (These steam passages are 
of such ample size that it is impossible that the heater 
should create any back pressure upon the engine, but, on 
the contrary, the partial condensation of the escape steam 
tends to relieve an engine of back pressure). The cold 
water is brought from a tank by pipe into the top of the 
heater, the supply being regulated by a suitable stop cock. 
Upon the end of this cold water pipe on the inside of the 
heater, and located just above and in front of the upper 
steam port, there is fastened a wedge shaped cup, called the 
overflow box. The water fills this cup and flows over its 
edges in a widely distended thin sheet, falliug down through 
the incoming current of steam onto the upper shelf. The 
steam passing thus through a thin sheet of water, dashes 
it into fine spray, acting upon each separate particle, and 
imparts to the water sufiicient heat to raise it to the boil- 
ing point, which sets free and precipitates the lime or other 
salts held in solution. The water now traverses a large 
area of heating and depositing surfaces, arranged in the 
form of removable shelves, having alternate openings. As 
the thin sheet of w^ater passes over these shelves, all of 
which are very hot, and descends from shelf to shelf, it is 
met in its downward course and constantly acted upon by 
the ascending current of steam which enters the heater at 
the low^er port. The action of this lower current of steam 
completes the separation and precipitation of the foreign 
particles which is begun when the water enters the heater. 



378 A TREATISE ON STEAM BOILERS. 

It will be observed that the construction of the heater is 
such that not a drop of water can pass down through it 
without being thoroughly boiled. The lime, magnesia, sul- 
phur, iron, silica, etc., which this process of boiling sets 
free from the water, are deposited in a crystallized state 
upon the entire series of shelves, the deposit always being 
heaviest upon the upper shelf and diminishing in quantity 
as it approaches the lower shelf. From the lower shelf the 
water, which has now parted with all that portion of its 
impurities which will crystallize, passes down behind the 
back of the filtering chamber into the mud well in the bot- 
tom of the heater, where the mud, sand, and uncrystallized 
particles of lime, etc., are deposited, and from whence they 
may be drawn off, through an opening for that purpose in 
the bottom of the heater, as often as may be necessary. 
The purification of the water is now completed by its pas- 
sage from the mud well upward through the false bottom 
and the filtering chamber C to its final exit from the heater 
at J. The filtering chamber is tightly packed with hay^ 
straw, or other suitable filtering material, which efi:ectually 
retains all the light floating particles not previously 
arrested. By the process thus described, water that is 
heavily impregnated with lime, magnesia, sulphur, iron, 
silica, clay, mud, sand, etc., is robbed of much these scale 
producing substances, and supplied to the boiler nearly 
boiling hot and almost pure. 

This system of filtering the water is one which efifec- 
tually removes mud, sand and all other impurities which 
will not crystallize and adhere to the shelves. As will be 
seen by referring to the sectional engraving, the water, 
after making the circuit of the shelves, passes behind the 
water shed directly to the bottom of the heater, thence up 
through the perforated plate, upon which the filtering 
material rests, and on up through the filtering material to 
the discharge pipe J. The great superiority of an upward 



STILWELL S LIME-EXTRACTING HEATER. 



379 



filter over a downward or side filter, all who have had any 
experience in this direction will readily admit. All the 
particles of mud and sand, instead of being dragged by the 
current of water through the filter, as in downward or 
side filters, settle readily to the bottom of the heater, from 
whence they are drawn ofi' or blown out through a waste 
pipe for that purpose. In some cases, when the water used 
is exceedingly muddy, the makers attach to the bottom of 
the heater a mud well and outside upward filters, with which 
arrangement they almost perfectly purify Missouri river 
water, which is well known as the muddiest water in 
the country. The writer has furnished a number of these 
combined heaters and lime extracters, in contracts which 
came under his superintendence, and from the very favor- 
able workings of the apparatus under many conditions, 
does not hesitate to recommend it as being, in the main, 
all that the manufacturers claim for it. 



TABLE LXXXXIII. 

PRINCIPAL DIMENSIONS OF STILWELL'S LIME-EXTRACTING HEATER AND 

FILTER COMBINED. 





















DIS- 




















TANCE 




LARGEST 






DISTANCE 


INTERNAL 


OUTSIDE 






FROM 




ENGINE 


HEIGHT 

OF 
HEATER 


DIAM- 


FROM 


DIAMETER 


DIAME- 


HOT 


COLD 


HOT 


StZE 


HEATER 


ETER 


CENTER 


OF 


TER 


WATER 


WATER 


WATER 


NO. 


IS 


OF 


OF STEAM 


EXHAUST 


OF 


PIPE 


PIPE 


PIPE 




ADAPTED 


HEATER 


INLET TO 


OPENINGS 


FLANGES 


J. 


C. 


J TO 




TO. 






BOTTOM. 


A AND B. 


A AND B. 






BOTTOM 

OF 
HEATER. 




IN. BORE. 


FEET. 


INCHES. 


INCHES. 


INCHES. 


INCHES. 


INCHES 


INCHES 


INCHES. 


3 


6 


4 


15 


28| 


2i 


5 


1 


1 


Hi 


4 


9 


5 


20 




3 


5J 


1 


1 


13} 


5 


12 


6 


24 


39^ 


5J 


8J 


li 


u 


17} 


6 


16 


7 


30 


49f 


7 


10} 


2 


n 


20^- 


7 


18 


8 


36 


53| 


8 


111 


2J 


H 


21 


8 


24 


9 


48 


58i 


10 


IH 


3 


2 


27 


9 


30 


10} 


48 


72 


lU 


15f 


4 


2 


27 



380 A TREATISE ON STEAM BOILERS. 

Green's heater^ as made by the Green Feed Water 
Heater Company, I^ew York city, is shown in vertical 
elevation in figure 154. Its operation will be easily under- 
stood from the following description : 

The cold water entering the heater by the pipe marked 
"cold water," passing through an open or poppet valve, as 
seen by cut, inside of heater, is thrown upon a perforated 
plate, through which it passes, falling in the form of rain 
or spra3^ The float operates upon said valve by compound 
levers, and so controls w^ith ample force, automatically, 
any pressure of the water coming into the heater, allowing 
no more water to enter than is wanted by the pump for 
the boilers, or for other mechanical purposes. The ex- 
haust steam enters at the bottom of heater through the 
large central pipe (which pipe corresponds in size with the 
exhaust pipe from engine), and striking against the disk 
seen at its top, is directed laterally against the falling 
spray of water, heating it almost instantly to boiling 
point. The surplus steam then passes around the 
perforated plate into the steam and water separating 
box, as seen at the top of heater. The hood or pipe inside 
of box deflects the steam against the sides and bottom, 
and by an expansion of the steam, drops to the bottom of 
box any water taken up from within the heater; the steam 
passing into the exhaust outlet is perfectly dry, while the 
water dropped from the steam, passes by a drip pipe to 
the body of the heater below. 

The water in heater flows out to the feed pump through 
the large pipe on the right, to which is connected an air 
pipe, in consequence of which it will be noticed that the 
body of water in heater can not be pumped down lower 
than the line marked lowest water line by pump, as 
when such level or line is reached the pump takes in air 
and steam. This lowest pumping line of water, holding 
upon its surface any dirt or grease, is removed daily by the 



EXHAUST 
OUTLET 

[11 




FiGURK l.")4. 



382 A TREATISE ON STEAM BOILERS. 

pipe and valve on the left marked surface blow, while 
the collection of dirt at the bottom of heater is removed 
weekly by the pipe and valve marked bottom blow. 

The float is constructed of copper on the outside, and 
is strengthened beyond the possibility of injury from 
either pressure or collapse, by a strong cedar barrel, well 
made and hooped, fitting the inside of float. The float 
thus constructed is perfectly reliable ; but as an additional 
safeguard, a spiral brass tube (called in cut a drip), 
is coupled to and enters the bottom of float, and passing 
down through the bottom of heater, acts as a drip in case 
of leakage, enabling the float to perform its duty until the 
leakage in float is greater than the capacity of drain by the 
drip. Furthermore, the atmosphere passing in and out of 
float by such brass tube, it becomes the means of safety 
against any tendency to collapse. 

An iron plate or apron is shown in cut just above the 
float, which protects the float from the pulsations of the 
steam, and ao, not only aids the float in keeping the water 
quite below, but the drops of water falling upon it from 
above, rebound, giving the steam another chance of heat- 
ing it before it passes off* at the sides to the well below. 

A water gauge and thermometer are furnished to each 
heater, the thermometer standing on the elbow of pipe to 
feed pump. Such thermometer is put in position that it 
may bear testimony constantly that the heater produces a 
uniform temperature of 210° Fahrenheit, or whatever may 
be the highest temperature possible by exhaust steam. 
Two large hand holes are provided in the upper part of 
heater, by which the valve and upper working parts of 
heater are reached with great readiness and efficiency. 
Also one large hand hole near the bottom, by which the 
drip pipe attached to float, and any accumulation of dirt 
in bottom of heater, can be readily handled. 



THE "victor"' heater. 



383 



The " Victor''^ heater, by Wm. Allen & Sons, Worcester, 
Mass., is shown in elevation in figure 155, and is a modi- 
fied form of the tubular 
heater so well known to 
steam users. 

This heater can be used 
with exhaust steam where 
there is sufficient or excess 
of exhaust, also with ex- 
haust and live steam com- 
bined, in a place where 
large heating capacity is 
required and but a small 
engine to run ; or with live 
steam alone, for heating 
water for boilers used in 
heating large public build- 
ings, hotels, etc. The great- 
est gain is made in fuel 
where exhaust steam only 
is used, but the heater will 
work equally well under 
either condition. When 
using exhaust, the steam, 
before leaving the heater, 
must pass through three sets ^ 
of tubes, each set beinsr the 
length of the heater, and 
each of greater area than 
the largest exhaust pipe, so that the engine is relieved 
and all liability of back pressure prevented. 

The heat causes the mineral and vegetable* matter, 
which is held in solution by the water, to settle in the bot- 
tom of the heater, and it is blown out through the pipe in 
the center of the bottom, at the same time opening the 




Figure IJo. 



384 A TREATISE ON STEAM BOILERS. 

live steam pipe in the top head so as to force the water 
down in a body, blowing out all sediment and dirt through 
the direct valve, which is easily reached, so that the work 
of purifying the water is attended with but little labor, and 
the fireman will prefer to use the heater and keep the boil- 
ers clean, rather than allow the sediment to settle in the 
boilers, and be obliged to remove it by chipping and pick- 
ing. The use of the heater prevents, in a degree, the for- 
mation of scale in the boilers. The heater delivers the water 
pure, at a temperature as high as 210" Fahrenheit, using 
only a portion of the exhaust steam, and does not interfere 
with the steam for heating. 

Stead's circulating generators for steam boilers, as man- 
ufactured by Ironclad Manufacturing Company, Brooklyn, 
New York, is shown in figure 156. Its arrangement and 
operation is as follows: 

A A is a series of heavy lap welded pipes, connected 
by return bends resting on bearers and forming a continu- 
ous close coil under the boiler, from bridge wall to back 
connection, making a chamber in which the combustion of 
gases from furnace is maintained and the flame held in 
close contact with boiler until it strikes the deflecting wall, 
which causes it to pass to under side of pipes, through 
which it returns into back end of boiler; by this means 
the heat is equalized on coil and sufficiently retarded to 
secure full eft'ect on boiler. The feed water enters the coil 
by pipe M and its connections, under the same conditions 
as to heat, etc., that it previously entered the boiler, and 
in its passage through coil it is heated to a temperature 
ranging from 240° to 310°, and enters tjie boiler through 
pipe I, as combined steam and water. J is a stop valve 
between coil and boiler, and K is a blow cock for clearing 
the coil. When the feed is stopped, the pressure in boiler 
gives fall opening to check valve L on pipe P, and the 



386 A TREATISE ON STEAM BOILERS. 

water from boiler passes down into the coil, through which, 
by its increasing temperature, it circulates with great rapid- 
ity to the boiler. By this means the coil is always filled 
with water, and can not be burned. The check valve L 
was designed for this purpose; it gives full and direct 
opening to pipe, and can not stick or fail to work perfectly. 

D is a riveted cast steel drum, taking the place of the 
brick bridge wall, which is lowered to admit it. The water 
from bottom of boiler passes through pipe ]^ to drum, 
where its temperature is raised much higher than that in 
the boiler, to which it returns nearly all steam, through 
pipes G H. By this means the intense heat at the bridge 
drum is utilized, and a rapid and continuous circulation is 
maintained. The lime and other impurities in the water 
can not settle and form scale, but pass down into the drum, 
from which they do not return to boiler, and are readily 
blown out through pipe F or removed at hand hole E. 

The blow off valve connected at this point is opened a 
minute or two each day, and in this way the sediment 
(before it hardens into scale) is as effectually blown out as 
if the entire amount of water were blown off. This is done 
while steam is being generated, and can be repeated as 
often as required. 

As a feed w^ater heater, this coil in the combustion 
chamber possesses advantages seldom secured, and results 
in raising the temperature of the feed water nearly or 
fully up to that in the boiler. The rapid and continuous 
circulation of water keeps the attachment free from scale. 

Economizers — This word, used in connection with the 
apparatus employed to recover waste heat passing off from 
the flues of the boiler into the chimney, is somewhat 
unfamiliar to American ears, though it is by no means 
new to those at all familiar with the leading English engi- 
neering journals. 





THE BABCOCK & WILCOX ECONOMIZER. 

FiGURE 157. 



ECONOMIZERS. 38T 



An economizer is usually understood to be an assem- 
blage of pipes in the smoke passage between the boiler 
and the chimney. Its object is to abstract heat from the 
escaping gases and turn it to useful account in heating the 
feed water. It would naturally be supposed that the boiler 
itself would be the best apparatus for heating water, and 
that little or nothing would be lost by pumping cold water 
into the boiler. 

This is not the case. Boilers, as usually constructed, 
are good steam generators, and act most efficiently when 
the feed water is of high temperature, nearly or altogether 
approaching that of the water in the boiler. Such an 
apparatus is far from being a good heater, because the 
temperature of the escaping gases, when leaving the tubes, 
is so nearly that of the contents of the boiler, that little 
or no heat is given up by the gases. In a properly made 
economizer, the cold water enters at one end of the appar- 
atus, and in passing through it takes up heat as it goes. 

The temperature of the escaping gases is not far from 
600°, on an average. If the steam pressure in the boiler 
is 75 pounds, the temperature will be 320°, or a difference 
of 280°. The rate of transfer of heat from the gases to 
the water within this range of difference will be slow, 
and hence will require a large exposure of surface to ren- 
der it of any value. 

An economizer is not to be regarded as merely equiva- 
lent to lengthening the boiler. The functions of the two 
are entirely different. Steam can be generated only at cer- 
tain temperatures, and when the temperature of the water 
falls below that due to the pressure of steam, ebullition 
ceases until the steam pressure is lowered to the corres- 
ponding temperature. 

The efficiency of the economizer is due to the fact that 
the temperature of the water within it is not the same 
throucrhout. The feed should enter at a point furthest 



S88 A TREATISE ON STEAM BOILERS. 

removed from the boiler; it here encounters the coolest 
gases, and, in its flow through the economizer, it takes up 
more and more heat, growing hotter as it advances, and is 
finally fed into the boiler considerably above the atmos- 
jpheric boiling point. 

The only circulation which an economizer should have, 
IS that due to the action of the feed pump, and the pipes 
should be as small as is consistent with good and safe 
construction 

An economizer, by Babcock & Wilcox, [N'ew York city, 
is shown in figure 157, and is, in some respects, an improve- 
ment over those in general use in England. It consists of 
a series of vertical tubes placed in a brick chamber, which 
forms part of the flue between the boiler and the chimney, 
and through which all the hot gases are caused to pass. 
These tubes are connected at top and bottom with hor- 
izontal tubes, the lower row of which are connected to a 
mud drum, and the upper row are connected together at 
the end diagonally opposite to the mud drum. The feed 
water enters at one end of the mud drum, and passes out 
at tbe opposite end of the upper connecting pipe. It will 
be seen that the water has the same distance to go, and 
the same resistance to encounter in whichever of the verti- 
cal pipes it may travel, and that, therefore, it will flow fast- 
est where its gravity is least, or directly as its temperature, 
and only the hottest portion will be discharged. The hot- 
ter gases, filling the upper portion of the chamber, come 
in contact with the water at its highest temperature, so 
that it is possible to heat the latter very nearly to 
the temperature of the escaping gases before it flows to 
the boiler. 

Ample provision is made for cleaning the interior of the 
vertical and horizontal tubes, and the mud drums by means 
of hand holes with metallic joints opposite the ends of 
each tube. This is important, as in most hard waters 



ECONOMIZERS. 389 



sediment will form in the economizer more readily than 
in the boiler. 

By means of a direct flue to chimney, the economizer 
may be cleaned without stopping the boilers. 

Mechanical scrapers, worked from above, are provided 
for removing deposits of soot from the exterior of the tubes, 
the soot falling into a chamber below, from which it may 
be removed at convenience. 

All joints in the construction of the economizer are met- 
allic, no packing of any kind being used, except for the 
large hand holes in the mud drum, and the parts are so put 
together that any one part may be removed and replaced 
without disturbing the other parts, and with comparatively 
little trouble. The tubes are made of cast iron, the expe- 
rience of years having proven that this is much the best 
material to resist the tendency to corrosion arising from 
the condensation of vapors upon their exteriors. Wrought 
iron has been found utterly unsuited to the purpose. 

Covering boilers and 'pipes — This is quite necessary, in 
order to save a great amount of heat which would other- 
wise be lost by radiation. There are quite a number of 
boiler coverings and cements, for this purpose, in the mar- 
ket. These are not all good. Figure 158 is a representa- 
tion of a section of pipe, as covered with the Asbestos air 
chamber covering, under the patent of H. W". Johns, New 
York city. These coverings are formed as follows : 

First apply the Asbestos lining felt to cover all surfaces, 
two thicknesses. It may be cut in lengths of one inch 
more than twice the circumference of the pipes, and wound 
twice around in sections, fastening each with a single 
turn of twine, then cut the hair felt crosswise of the 
sheet in strips, one inch larger than the circumference ot 
the covered pipe, and bind flrmly over the lining felt with 
twine, winding spirally four or Ave turns to the running 



390 



A TREATISE ON STEAM BOILERS. 



foot ; next, cut the non-porous sheathing crosswise of the 
sheet, in lengths two or three inches larger than the cir- 
cumference of the hair felt. Tie temporarily, and paste 
the lap with common flour paste, and apply carefully so 
the surface will he smooth. This, when finished with a 




FlGURK 158. 

fire'^^ proof paint, forms the single chamher, w^hich is suita- 
ble for small pipes, or where less then 40 pounds^of steam 
is used. 

To form double or triple chambers, add alternate lay- 
ers of hair felt and non-porous sheathing. To finish these 
coverings, paste bands of non-porous sheathing about two 
inches wide over the joints, being careful to put them on 
true. This adds to their strength, and forms a handsome 
finish. 



i 



COVERING BOILERS AND PIPES. 



391 



Elbows and tees should be covered with.canvas or drill- 
ing before finishing with the non-porous sheathing, which 
should always overlap the can- 
vas. After the pasted joints 
are dry, finish the whole with 
fire proof paint. 

These instructions also ap- 
ply to covering boilers or other 
large surfaces, except, that the 
whole should be covered with 
canvas. This covering has, so 
far, produced very satisfactory 
results on general pipe work. 

Another kind of covering, 
manufactured by the Chal- 
mers-Spence Company, E'ew 
York city, is shown in figure 
159, in its application to boil- 
ers ; it consists, first, in leav- 
ing an air space or dead air 
chamber between a wire cover- 
ing and the surface covered ; second, in the keying of some 
plastic material on the wire cloth; and third, in giving a 
double check to radiation by the confined air and the non- 
ducting composition. There are numerous other advan- 
tages which might be mentioned, but the above named are 
the most prominent. The air space is made by taking 
heavy wire cloth, to which is fastened, every four or ^ve 
inches, a stud one inch or more in length. The wire cloth 
is then fitted over the surface to be covered, the studs 
keeping it the necessary distance off. The plastic material 
is next applied, in two or more coats. The first coat partly 
penetrates the meshes of the wire cloth and keys itself, 
obtaining a strong, durable hold. The second coat makes 




FiGURK 159. 



392 



A TREATISE ON STEAM BOILERS. 



a smooth, even Unish, which may be painted, grained, or 
varnished, as may be desired. 

There are many objections to applying a covering direct 
to the surface of the boiler, for it has been found, especially 




FiGURK 160. 



in marine boilers, that, when so covered, the inside as well 
as the outside of the boiler rapidly scales. The air space 
method, we are informed, is not open to these objections. 
On the contrary, it keeps the iron clean and bright, besides 
preventing the radiation of heat and condensation of 
steam. 

Figure 160 shows the application of the same covering 
to steam pipes. Tests made with this covering show it to 
be an effective means of preventing loss by radiation. 



CHAPTER XV. 



SAFETY APPARATUS. 

Safety Valves — Dangerous Connections — Combined Safety and Stop 
Valve — Richardson's Safety Valve — Ashcroft "Pop" Valve — Crosby 
Safety Valve — Lunkenheimer's Safety Valve — Kunkle's Safety 
Valve — Pressure Gauges — Bourdon's Gauge — Lane's Gauge — Dia- 
phragm Gauges — Holt's Gauge — Post & Co.'s Gauge — Edson's 
Recording Gauge — Gauge Cocks — Glass Water Gauges — Fusible 
Plugs. 

The safety apparatus commonly attached to steam 
boilers consists of a safety valve, gauge cocks, glass water 
gauge, pressure gauge and a fusible plug. 

Safety valves — A safety valve should be of such size as 
will enable the escape of all the steam which the boiler is 
capable of making, without increasing the pressure in the 
boiler over ten to fifteen per cent above that to which the 
valve may be loaded. 

Rule 1 — The United States regulations require that 
safety valves for ocean and river service " shall have an 
area of not less than one square inch for each two square 
feet of grate surface, when the common safety valve is 
employed. 

" Rule 2 — But when safety valves are to be used, the 
lift of which will give an effective area of one-half of that 
due the diameter of the valve, the area required shall not 
be less than one-half of one square inch to two square feet 
of grate surface." 



394 A TREATISE ON STEAM BOILERS. 

The grate surface seems to be, all things considered, the 
best unit of measurement for determining the size of 
safety valves. The ordinary rate of combustion may be 
placed at, say 14 pounds of coal per square foot of grate, 
and the rate of evaporation may be taken at ten pounds of 
water per pound of coal, as the maximum. There are 
many formulas bearing on valve proportions, but those 
given in the United States regulations are easily remem- 
bered and ample in size for any requirement. 

The grate surface for a 48-inch boiler, as given on page 
246, is 20.6 square feet; this would require an area 10.3 
square inches for a common valve, or 3f inches in diame- 
ter. If figured by the rule in the next paragraph, the area 
would be 5.15 square inches, or 2f inches diameter. 

The writer does not recommend safety valves of a 
greater diameter than four inches. The area of a valve 
increases as the square of its diameter. The circumfer- 
ence increases directly as the diameter. The escape of 
steam is around the circumference, and it will be under- 
stood, of course, that a point would soon be reached in 
which the area would be of little account if carried to 
large diameters and figuring on ordinary valves. For 
example, if the grate [area required a common valve eight 
inches diameter, it would have a circumference of 25.13 
inches; the same area would be furnished by four 4-inch 
valves, the combined circumferences of which would equal 
50.26 inches, or twice the circumference for the same 
area. An 8-inch valve is an extreme case, but it illustrates 
the point. 

Each boiler should have its own safety valve. It should 
be connected directly to the shell, and in no case should 
there be a stop valve between it and the boiler. The writer 
happened to be in a large establishment not long since, in 
which he saw the boilers connected together by means of 
a steam drum having stop valves in the boiler connections, 



SAFETY APPARATUS. 



395 



and one safety valve on the top of the drum to serve for 
the two boilers. The attention of the owners was at once 
called to the great danger which might accrue from an 
unintentional closing of both valves. In looking over an 
annual report of the Hartford Steam Boiler Inspection and 




Figure 161. 



Insurance Company, the writer saw an engraving of a pre- 
cisely similar connection, with the record of the disastrous 
results following. Through the courtesy of Mr. J. M. 
Allen, president of the company, the writer is enabled to 
place before the reader copies of the engravings referred 
to. Figure 161 shows the original condition of the boilers : 
" It appears that for some reason one boiler had been 
shut off, and the steam gauge between the boilers had been 



396 



A TREATISE ON STEAM BOILERS. 



removed for repairs. The boiler was fired up, and a 
destructive explosion occurred. Fortunately, no lives were 
lost. There are many boilers through the country set in 
this way, and serious accidents have occurred and will 
occur so long as this practice is followed. Portions of the 
boiler were thrown from 300 to 700 feet. The following 
figures will show the manner in which the iron was torn : 




Figure 162. The top of the steam drum. 




FiGuitK 163. Rear end of the left hand boiler, which was thrown some 225 feet. 



SAFETY APPARATUS. 



397 




Figure 164. Front end of the left hand boiler. 

A combined safety and stop valve, by the Atlas Engine 
Works, Indianapolis, Indiana, is shown in figure 165. By 
an inspection of the engraving it will be seen that the stop 
valve may be opened or closed without, in any manner, 




Figure 165. 



398 



A TREATISE ON STEAM BOILERS. 



afiecting the safety valve. The valve is shown with a lever 
attachment, but a spring may be used instead. This is an 

excellent form of con- 
struction, and will en- 
able any particular 
boiler in a battery to 
be shut off from the 
others, and, in the 
event of steam being 
raised, it will take care 
of itself. 




The Richardson safe- 
ty valve is shown in fig- 
ure 166. This engrav- 
ing shows the usual 
mode of attachins: the 
valve to the dome head 
of a locomotive boiler. 
A A, being the cast- 
iron head ; B B, a gun 
metal bushing ; C, the 
valve fitted with an 
annular adjustabla lip 
C. The valve is lifted 
from its seat by the pressure which, in escaping around the 
circumference of the valve, impinges against the interior of 
the chamber formed by the projection of the valve, and by 
this adjustable lip, which, in effect, increases the area of 
the valve not only, but the steam acts against it with 
much greater force after it lifts it from the seat than before. 
Notches, K, are provided in the ring for adjustment, and 
secured by screws, L. The tension of the spring, F, is reg- 
ulated by the nuts, II, and cross head, G. 

A self contained valve and case for stationary and 
marine boilers, without the adjustable lip, is shown in fig- 



FlGURE ll3(3. 



ASHCROFT SAFETY VALVE. 



399 



ure 167 ; its action is the same as the one already referred 
to. These may be fitted with a lock up device, as shown ; 
the valve may be set at any required pressure, and the 
case locked up, and thus preventing access to the valve or 
spring, except to those having the key. The lever may be 
used to test the valve, but can 
not be made to bear down up- 
on it. 

The Ashcroft ^'pop^' safety 
valve — This valve is shown in 
elevation in figure 168, and in 
partial section in figure 169, 
which shows one of the dis- 
tinctive features in the valve 
construction — that is, the nick- 
el seat. The valve seat, and 
that portion of the valve which 
bears upon it, are made of hard 
nickel bronze, which may be 
made as hard as steel, and yet 
suffers no corrosion by the ac- 
tion of either the steam or the 
air. The " 



pop" receives its 




Figure 167. 



name from the sound it emits 
when suddenly opened under 
pressure. This can also be made a lock up valve by mak- 
ing a dome to cover the upper works, and bolting to the 
flange at A D. 

A special valve for portable and other small boilers is 
shown in figure 170, and is in all essentials the same as 
those already described. 

The Eichardson and the Ashcroft patents are now con- 
trolled by one company, under the name of the Consoli- 
dated Safety Yalve Company, Boston, Mass. 



400 



TREATISE ON STEAM BOILERS. 



The Crosby adjustable pop 




Figure itiS. 



seat, W W, is not acted upon 
The large seat, V V, is 
formed on the upper edge of 
the shell or body of the valve 
A A, The smaller seat, W 
W, is formed on the upper 
edge of a cylindrical cham- 
ber or well, C C, which is 
situated in the center of the 
shell or body of the valve, 
and is held in its place by 
four arms, D D, radiating 
horizontally at right angles 
to each other, and connect- 



safety valve is shown in ver- 
tical elevation in figure 
171. The valve proper, 
B B, rests upon two flat 
annular seats, V Y and 
W W, on the same plane, 
and is held down against 
the pressure of steam by 
the steel spiral spring S. 
The tension of this spring 
is regulated by screwing 
down the threaded bolt 
L, at the top of the cylin- 
der K. The area con- 
tained between the seats 
W and V is what the 
steam pressure acts upon, 
ordinarily, to overcome 
the resistance of the 
spring. The area con- 
tained within the smaller 

at all until the valve opens. 




FiGUKK 109. 



THE CROSBY SAFETY VALVE. 



401 



ing it with the body or shell of the valve. These arms are 
hollow and form four passages, E E, for the escape of the 
steam or other fluid from the well into the air when the 
valve is open. This well is 



deepened so as to allow the 



w 



ings, 



X X of the valve 



proper to project down into 
it far enough to act as guides. 
The area of the apertures, 
at the outer ends of the pass- 
ages through the arms is re- 
duced more or less at will, 
by screwing up or down the 




Figure 170. 




«%Kia3£Zz amc/fAftosGf/ sc. 



Figure 171. 



adjustable ring G G. Action of the valve when working 
under steam: When the pressure under the valve is 
within about one pound of the maximum pressure re- 
(27) 



402 



A TREATISE ON STEAM BOILERS. 



quired, the valve will open slightly, and the steam will es- 
cape under the larger seat into the cylinder surrounding the 
spring, thence into the air; the steam is also forced under 

the smaller seat into the 
well and thence through 
the passage in the arms 
into the air. As soon as 
the pressure attains the 
exact maximum point, 
the valve will be lifted so 
high as to force the steam 
into the well faster than 
it can escape through the 
apertures in the arms; a 
pressure will then accu- 
mulate under the inner 
seat, which will be in ex- 
cess of what was required 
to overcome the increas- 
ing resistance ofiered by 
the spring, and acting 
upon the additional area- 
presented, at once forces 
the valve wide open and 
rapidly relieves the boil- 
er. This pressure under 
the inner seat is of itself 
diflerential. The valve 
then at once slowly set- 
tles down and the press- 
ure under the inner seat 
as slowly diminishes, and 
so continues until the 
area of the opening, under the smaller or inner seat, is less 
than the area of the apertures in the arms for the escape of 




A. 
Figure 172. 



kunkle's safety valve. 403 

the steam; the pressure then ceases and the valve promptly 
closes. The point of opening can be readily changed while 
under steam by screwing the threaded bolt at the top of the 
cylinder, either up or down; and the point of closing is as 
easily adjusted, by screwing up or down the ring surround- 
ing the outside shell or body of the valve. The seats of • 
this valve are flat and do not wear out and leak so readily 
as beveled seats. 

This valve is made by the Crosby Steam Gauge and 
Valve Company, Boston, Mass. 

An adjustable lock up safety valve by F. Lunkenheimer, 
Cincinnati, Ohio, is shown in figure 172. 

The valve B has an annular projection beyond the seat 
and fitted on its upper side with a concave step to receive 
the point of the stem shown above it. 

The manner of loading the valve is novel and simple, 
80 no mistakes are likely to occur. Every valve is set to 
ninety pounds and so marked, unless otherwise ordered. 
The change of the load is effected by a series of washers P 
between the spring plate C and set screw E. 

Each washer added will increase the load ten pounds; 
each washer taken ofiP will reduce the pressure ten pounds. 

The valve when locked can be lifted at will, but can 
not be loaded, being prevented by a shoulder in bonnet 
at S. When taking the valve apart, remove the lock, lever 
and bonnet, and raise the set screw E, so as to relieve the 
spring, then insert the lever H in the fulcrum, and the cas- 
ing or shell is easily unscrewed. 

Before adding the bonnet, keep the set screw well down 
to its shoulder. 

A lock up safety valve by E. B. Kunkle, Fort Wayne, 
Ind., is shown in figure 173. The spring is set between 
two tapered points, enclosed in the valve with sufiScient 
room to allow it to curve when weighed down, which pre- 
vents all friction, securing the spring from being over- 



404 



A TREATISE ON STEAM BOILERS. 



heated by the steam so as not to weaken it ; the top end 
of the valve is enclosed by a flange underneath the cap, 
thus protecting the spring from the steam, sediment and 
cinders, when used on locomotives, keeping it entirely 
clean at all times, making it reliable under constant action, 
which can not always be the case with springs exposed to 
the steam and weather. 



TABLE LXXXXIV. 

DIAMETERS FOR SAFETY VALVES, ACCORDING TO RULES 1 AND 2, 

PAGE 393. 



AREA OF GRATE SURFACE, 


DIAMETER FOR COMMON 


DIAMETER FOR VALVE, 


IN SQUARE FEET. 


VALVE, BY RULE ONE. 


BY RULE TWO. 




INCHES. 


INCHES. 


5 


15 
^4 


1 


6 


2 


1 


7 


2i 


1 


8 


2i 


H 


9 


2| 


H 


10 


2^ 


n 


12 


2| 


•If 


14 


3 


H 


16 * 


H 


-H 


18 


3| 


If 


20 


^ 


If 


22 


3| 


H 


24 


3i 


2 


26 


4 


2 ■ 


28 


4i 


2i 


30 


41 


2^ 


32 


^ 


2i ■ 


34 


4| 


2| 


36 


4f 


2| 



i 



PRESSURE GAUGES. 



405 



The uniform bearing of the valve upon its seat hy 
son of the long ribbed chamber pre- 
vents the valve from capping upon 
one side and causing the steam to 
cut away the seat. 

The outside regulator can be ad- 
justed when the valve is blowing 
off, so that it will act with a sudden 
report, or open and close gradually, 
with little or no report. It is pro- 
vided with a screw-bolt resting on 
the plate on top of the spring, and 
jana nut holding it firmly to its 
place ; the top of the bolt being 
adapted to receive a lead seal, which 
makes it doubly safe from being 
tampered with. 



rea- 




Figure 173. 



Pressure gauges properly belong to the safety apparatus 
of a boiler, although performing no other service than 
simply to indicate the pressure within the vessels to which 
they are attached. As great reliance is often placed on the 
steam gauge, it is of the utmost importance that it be of 
approved design and of the very best quality. Steam 
gauge pipes should not be attached to a steam pipe, but to 
the top of dome, drum or boiler. 

It not unfrequently happens that the safety of an entire 
establishment depends upon the reliability of this instru- 
ment and on the safety valve. The latter is not always 
convenient of access, and is liable to be neglected; the 
steam gauge, on the contrary, is always placed in some 
convenient position, and is consulted every few minutes 
when the boilers are in use. The writer has known of 
instances in which gauges had been in use for a long time, 
and upon submitting them to a test, many were found to 



406 



A TREATISE ON STEAM BOILERS. 



be SO far in error and so unreliable in tbeir readings as to 
be utterly worthless; in one instance in particular, a gauge 
marking nearly twenty-four pounds per square inch too 
little, the pointer starting from in every case, when 
relieved of pressure. This was a finely finished, high 
priced gauge, and was believed to be correct until it was 
submitted to a test. 

Every steam gauge should be tested at least once a 
year, to be sure that it indicates the pressures correctly. 

Spring gauges have for many years past been in very gen- 
eral use in this conn- 
try, most of them be- 
ing either direct cop- 
ies or some modifica- 
tion of the original 
Bourdon gauge, il- 
ustrated in figure 
174. This gauge 
consists of a curved 
tube, usually of brass, 
though sometimes of 
steel, having an ellip- 
tical cross section, 
thus: O. One end 
of this tube is rigidly 
fastened to that por- 
tion of the instrument by which communication is had 
with the steam pipe; the other end is closed and left free 
to be influenced by the pressure within the tube. The 
action of this internal pressure on the tube is to change 
its transverse section from an ellipse to that of a circle. 
This change of section disposes the metal difierently in 
the tube, and has a tendency to straighten it, and being 
fixed at one end, the other moves outward from the 




Fl(iUKK 174. 



PRESSURE GAUGES. 



407 



original position occupied when free from pressure. The 
distance at which this free end of the tube will move 
depends entirely upon the pressure within it ; advantage 
is taken of this movement to record on a circular dial 
the pressure found necessary to produce certain move- 
ments. These curved tubes may be made of any desired 
tension, the thinner 
the tube the less will 
be the pressure re- 
quired to produce 
a movement. The 
thicker the tube 
the greater will be 
the pressure requir- 
ed, so that gauges 
may be constructed 
on this principle in- 
dicating very slight 
pressures above the 
atmosphere, or, by 

the suitable selection Fiuuui. x^o.-^ 

of a tube, they may be made to register the highest press- 
ures of the most powerful hydraulic presses. 

Steam gauges usually have a siphon attached to pre- 
vent the steam entering the tube. This siphon collects a 
body of condensed water within it, against which the 
steam acts on the one side, and through its action the 
pressure is communicated to the elliptical tube. During 
the winter months the tubes in the Bourdon gauges are not 
unfrequently split, or else so disturbed by the freezing of 
the water as to produce false readings. This defect in the 
original Bourdon gauge was wholly remedied in the modi- 
fied construction designed by Mr. Lane, whose gauge is 
shown in figure 175. 

-This engraving, and the one preceding, are from designs by the American Steam 
Gauge Co., Boston, Mass. 




408 A TREATISE ON STEAM BOILERS. 

This gauge differs from the one just described in so 
combining the indicating tube with the pipe through which 
the pressure is transmitted, in such a manner that the 
length of the tube in either direction from its junction 
with the steam pipe shall not exceed a semi-circle, and 
placing the tube in such a position that it shall descend at 
any point towards its junction, and thus drain any water 
it may contain back into the pipe. 

By joining the pipe from the boiler with the indicating 
tube at a point nearly midway between its two ends, and 
bendino^ this tube so that the ends shall be nearly over the 
points where its two branches are rigidly supported, the 
tube is rendered less sensitive to the vertical shocks to 
which it may be subjected, especially in locomotive use. 

By bending the two portions of the indicating tube 
symmetrically, or nearly so, upon the opposite sides of a 
vertical line, and then connecting the two extremities of 
the tube with the lever, as shown in the engraving, will 
prevent the horizontal vibrations of the tube from being 
transmitted to the index hand, the lever being pivoted to 
the indicating tube, and is not attached to the case, this 
latter being an important feature in its construction. 

Diaphragm gauges, are those in which there is a cavity 
or chamber in some portion of the mechanism (usually 
immediately below^ or in the back of the case), in which 
the pressure is applied on one side of a flexible partition, 
the effect of which is to "dish" it in the center; this force 
is opposed on the other side by a spring, or other 
device; in those gauges in which the partition (the dia- 
phragm) is not strong enough to resist the pressure, a 
movement of the diaphragm will take place. This move- 
ment corresponds to certain pressures which are to be 
marked on the dial of the gauge. 



PRESSURE GAUGES, 



409 



This principle of construction admits of almost num- 
berless combinations, and as a result scores of these 
gauges have been designed, ranging everywhere in excel- 
lence from good to bad. The principal defect in these 
gauges, where a metal diaphragm is used, is, that continued 
use soon destroys the elasticity of the diaphragm in those 
gauges where its movement in the center amounts to J 
inch or more. Many experiments have been made from 
time to time, to determine the best system of corrugations 
for the diaphragm, for 
upon its efficiency and 
durability depend the val- 
ue and reliability of the 
gauge itself. 

Figure 176 is a modi- 
fied form of a diaphragm 
gauge by Mr. John P. 
Holt, Cleveland, Ohio, in 
which 1 represents a brass 
plunger which rests up- 
on a flexible diaphragm, 
shown immediately below 
it. The upper end of this 
plunger is attached to 
a semi-circular spring 
which extends across the 
case as shown at 2; a lever 3, having a fulcrum attached 
to the case, is operated by the action of the plunger 1, and 
thus through the action of the intermediate mechanism, 
shown in the center of the engraving, the upward motion 
of the plunger is indicated on a circular dial, and corres- 
ponding pressures read ojQF in the usual manner. 

The prominent feature in this gauge is the placing of 
the spring 2 inside of the case and out of contact with 
steam or moisture. The rise of the brass plunger is, in 




Figure 176. 



410 



A TREATISE ON STEAM BOILERS. 



Mr. Holt's practice, reduced to about -Jg- inch. This gauge 
is quite sensitive in its action, and is well liked by locomo- 
tive engineers on account of its being able to withstand 
the jarring incident to railway service. 

Figure 177 represents an internal front view of a dia- 
phragm gauge by Post & Co., Cincinnati, Ohio. A por- 




FlGURE 177. 



tion of the follower D, is removed in. order to show the 
position of the diaphragm, with reference to the mechani- 
cal movement which transmits the vibration of the dia- 
phragm to the pointer or registering hand. This is better 
shown in figure 178, which represents a perspective sec- 
tional view of the whole mechanism of the gauge, with 
the exception of the pointer and graduated dial. 

The steam enters the gauge at A and passes through 
into the chamber B ; a diaphragm, C, is securely fastened 



PRESSURE GAUGES. 



411 



about midway in this chamber by screwing down the fol- 
lower D firmly upon it. A thin, soft metallic gasket, 
shown by the parallel lines immediately below the section 
of the diaphragm at D, insures a tight joint, and prevents 
the steam passing through into the body of the gauge. 




FIGURE 178. 



The diaphragn is, of course, the important thing in 
any gauge of this description. Heretofore the great 
trouble has been experienced by the diaphragm yielding 
somewhat at the joints, by slightly drawing out, so that 




FlGUKK 179. 



at different times, under the same pressures, the gauge 
would indicate difi:erent readings. This difliculty is over- 
come by making the surfaces of the joint to incline up- 
ward, so that when the follower D is screwed down upon 
the diaphragm and the steam impinges upon its lower sur- 
faces it will tighten the metal within the joint instead of 



412 



A TREATIES ON STEAM BOILERS. 



permitting it to yield, and will at the same time lessen the 
possibility of any leak of steam. This detail of construc- 
tion is shown in figure 179. 

The diaphragm in this gauge is a radially corrugated 
steel disk, and is compensating in its movement, in that, 

when the pressure is ap- 
plied, it has a motion 
which shows it to be sen- 
sitive to the most deli- 
cate pressure. This mo- 
tion distributes the ex- 
pansion or strain on the 
fibers of the steel through- 
out the whole area of the 
disc, instead of having, as 
in ordinary discs, all the 
strain come upon which- 
ever corrugation may be 
the weakest. 

This peculiarity of con- 
struction was put to a 
severe test during the 
Cincinnati Exposition of 
1872, by subjecting one 
of these gauges to an accumulating pressure until fifteen 
hundred pounds had been reached, and this, without " set- 
ting" the spring or affecting its accuracy. 

Figure 180 is a full size representation of the follower 
D, and exhibits so clearly the registering mechanism as to 
need little or no description. 

The lever E rests upon the center of the diaphragm, and 

is kept in contact with it by means of the spiral spring E. 

The pressure of steam in the chamber B (see figure 

178), presses the center of the diaphragm C, outward ; this 

raises the lever E, which has indirect connection with the 




Figure 180. 



RECORDING GAUGES. 413 



sector and pinion, as shown. This pinion shaft carries 
the pointer indicating the pressure of steam on a graduated 
dial in the usual manner. 

Recording gauges — The objects for which recording 
gauges are designed, among others, are, 

1. To save life, by furnishing a monitor or check upon 
all those in charge of steam machinery, on land or water^ 
inciting them to utmost vigilance and care. 

2. To furnish an engineer means of obtaining an 
indubitable voucher of his capacity, as well as of his fidel- 
ity in the discharge of his responsible and important duties, 
and an impartial umpire to refer to when disputes or dif- 
ferences occur. 

3. In cases of disaster, to ^^ the responsibility where 
it properly belongs. 

4. To effect a saving in fuel by regulating the pres- 
sure, and thereby to diminish injurious strain on the boiler, 
and wear and tear of machinery. 

5. To assist inspectors in arriving at the actual condi- 
tion of the boiler, by showing the treatment it has sus- 
tained, as well as to enable them to judge to the fitness 
and reliability of engineers, when granting. licenses. 

6. To secure any desired degree of heat by maintain- 
ing the relative proportion of steam pressure necessary in 
factories, drying establishments, hotels, public schools, etc., 
where the proper regulation of the temperature is indis- 
pensable. 

7. To afford reliable and tangible data for scientific 
and other investigations; for which purposes these "charts'* 
or "steam logs" should always be dated and filed away, 
on removal, for future reference. 

.Figure 181 represents in elevation a time pressure and 
speed recording gauge, by M. B. Edson, New York city. 



414 



A TREATISE ON STEAM BOILERS. 



This gauge gives dial indications and accurate diagrams 
of all pressures ; the charts define the time, and the safety 

alarm is sounded whenever 
the limit specified shall be 
exceeded. 

An " electro - magnetic 
alarm apparatus" will be 
furnished at a small extra 
cost, which rings a gong at 
the boiler whenever and as 
long as excessive pressure 
exists. The gong and mag- 
net and batteries are shown 
in figure 182. 

The gauge should be 
placed upon the shelf, sup- 
ported by the brackets and 
firmly secured to a wall or 
partition of the office (or 
other room) where it is de- 
sired to place it, and about 
4 J feet from the floor. The 
aperture underneath (to re- 
ceive the steam or other 
pressure) is intended for a J-inch pipe with, a bent tube or 
siphon. 

The clock should be fully wound every day at the time 
of removing the portion of the chart traced upon.. 

The pencil lead is held by means of a slotted point in 
the thumb-screw (at the lower end of the spring holder) 
and may be pushed inward or withdrawn (after adjusting 
the screw), so as to give a clear tracing of every fluctuation 
indicated by the "pointers" on the vertical and upper 
scales. 




Figure 181. 



RECORDING GAUGES. 



415 



The (toothed) friction plate upon the right hand reel 
should be released (by unscrewing the thumb-nut), in order 
that the chart traced upon may be removed and a fresh por- 
tion drawn forward. After the new end has been inserted 
in the slot in the reel and adjusted to the proper clock 
time, the nut should again be screwed down upon the ree- 




Figure 182. 



just sufficiently to rotate the same, care being observed 
not to press so hard as to retard the movement of chart. 

If the pencils become hard, soften by soaking in oil, 
bearing in mind that too great pressure upon the chart by 
the pencil will retard and may stop its movement. 

Keep the chenille at the bottom of the glass dome 
pressed down to protect the instrument from dust. 

When the gauge is used to indicate pressure of steam, 
water or oil, and is placed above the boiler or reservoir, 
deduct say one pound from the indicated pressure for 
every two feet in the difference in elevation ; when below 
the level, add at the same rate. 

The distance from the boiler longitudinally may be 
extended several hundred feet without materially affecting 
the indication of pressure. 

The alarm movement is wound by a key from the front. 

The alarm may be adjusted to ring at any point of 
pressure desired, by menus of the long screw, which will 
be seen immediatelv behind the dial. 






I 'vto: V iioTi ad 
rpi q )nt 



J 3d 3j|n8^3ic! 















J9< 



JO} 



aatp ' 



'80 19: 9jas ei 1) ij 



jfjlBp 



«?!-■ 



--ft 





■f4 



k 



uoln 






-jj 



Figure 183. 



Figure 184. 



RECORDING GAUGES. 417 



The horizontal lines on the chart generally indicate 
every ten pounds of pressure, each chart being specially 
ruled to correspond with the exact indication of the pres- 
sure by the hand on the dial. 

The portion of chart recorded on should be removed 
daily, dated and carefully preserved for reference. 

The automatic tracing upon the chart should, on no 
account, be re-traced, as that would effectually destroy its 
integrity. 

Reduced fac-similes of charts actually made are shown 
in figures 183 and 184. 

The speed recording apparatus is specially adapted for 
factories, mills, etc., w^here the maintenance of any definite 
rate of motion is required ; and upon railways and steam- 
boats generally, where economy, safety, time and speed, 
each and all should receive special supervision (as they, 
alike, demand every possible protection against the results 
of ignorance, carelessness and recklessness in which the 
entire community is interested), they are of necessity 
indispensable. It is obvious that charts automatically 
traced, which contain evidence of the rate of speed of a 
train, or the rate of motion of machinery, and whereon 
the degrees of steam pressure carried is written, and 
which, furthermore, defines the clock time occupied by 
any given performance, ofier a combination of evidence 
at once impartial and exceptionally complete and incontro- 
vertible, and must in all future time be of great practical 
value. 

The records may be secured against tampering by a 
band passing over the glass dome, or may be entirely con- 
cealed from view, when such precaution shall be deemed 
judicious. 

These speed records are made by means of a small 
governor, forming a part of the instrument and shown 
(28). 



418 A TREATISE ON STEAM BOILERS. 

attached below the shelf in figure 181. A small grooved 
pulley is also shown, by which it is driven. 

Place the belt in the groove of the pulley (which is 
four inches in diameter) and so adapt all other pulleys 
as to secure the desired number of revolutions (or rate of 
motion), the maintenance of which will result in a uni- 
formly traced horizontal line upon the chart. Any curva- 
tures, either above or below such fixed line, will show the 
extent of all variations of speed according to the degrees 
upon the vertical scale and corresponding lines of the chart* 

The vertical subdivisions on the chart define the hours, 
or clock time, and the ruled horizontal lines define each 
successive five or ten pounds of pressure upon the gauge, 
from zero up. 

By slightly moistening the speed records they become 
more distinct, and will be rendered indellible. The difi:er- 
ence in the color of the tracings will prevent confusion. 

Gauge cocks — Each boiler should be provided with at 
least three; the middle one on the water line, the lower 

one at least one inch above the crown 
sheet, or top of flues, and the upper 
FiGURK 185. one at any convenient height, ac- 

cording to the construction of the boiler. There are a 
great variety of gauge cocks in the market to select from. 





Figure i86. 



Compression gauge cocks are perhaps the best for port- 
able engines and locomotives; the "Mississippi" gauge 
cock, shown in figure 185, is an excellent one for station- 
ary boilers. A modification of the latter gauge cock is 



WATER GAUGES. 



419 



made by A. W, Cadman & Co., Pittsburg, Pa., and shown 
in figure 186. 

By reference to the cut it will be seen that the valve 
and seat is placed at the end most remote from the boiler, 
thus avoiding the common result of twist- 
ing the valve seat out of shape when put- 
ting into the boiler. The valve being plac- 
ed away from the heat of the boiler, it can 
not be stuck fast by a formation of scale, as 
is frequently the case. There being no 
circulation of water in the shank (except 
when blowing), there can be no danger of 
its stopping up with sediment. The valve 
stem being so short it is impossible to bend 
or break it with the gauge stick. 

Glass water gauges — The commonest 
form of such a gauge is shown in figure 
187. In fixing it to the boiler the top of 
the lower stuffiinsc box o^land should be at 
least an inch above the crown sheet or top 
of the flues. figure is?. 

This will place the level indicated by this gauge and 
the lower gauge cock in the same plane. This attach- 
ment consists essentially of two connections fitted with 
valves, one for the steam and one for the water; the latter 
is further provided with a pet cock to test the lower open- 
ing. The glass tube passes through a stuffing box at each 
end. An ingenious device, shown in figure 188, is by Aug. 
P. Brown, New York city, which consists of a ball placed 
in each connection, and of such size as not to prevent 
the steam and water passing freely into the glass tube; 
yet, in the event of its breakage, the current of water and 
steam will carry the balls outward and close the passages 
leading: to the tube. This will allow the insertion of a 




420 



A TREATISE ON STEAM BOILERS. 



new tube, when, bj the action of the screw B on the valve 
A, communication is again made with the boiler. 



Fusible plugs should be attached to the crown sheet of 

all internally fired 
boilers, and are often 
attached to the up- 
per side of the flues 
in externally fired 
boilers. They con- 
sist merely of a brass 
shell filled with ban- 
ca tin,orothermetal 
melting below the 
red heat of iron. 

The object of a 
fusible plug is to 
melt when the water 
in the boiler be- 
comes dangerously 
low, and are placed 
over the fire box 
that the contents of 
the boiler may be 
emptied into it and 
put the fire out. 

Fusible f>lugs are 
often rendered in- 
operative because 
they become cover- 
ed over with scale, 
which may be of suf- 
ficient thickness to 
Figure 188. withstand the pres- 

sure of steam after the metal has been melted below it. 




SAFETY PLUGS. 421 



To avoid the possibility of the safety plug becoming 
inoperative through the accumulation of scale over it, a 
device for its protection is shown in figure 79, p. 284. 
The plug is contained in the pipe 3 at a point shown by an 
enlargement of the pipe about half way up from the bottom 
of tlie boiler, and above it a continuation of the same pipe 
extends upwards beyond the water level, so that as the 
water never comes in contact with the metal there is no 
chance of scale ever forming over the metal of the plug. 
The security against the water falling dangerously low, 
afforded by the use of the safety plug,^has been fully 
appreciated, but when improperly made or set they may 
become a source of danger instead of safety. 



CHAPTER XVL 



INCRUSTATION AND CORROSION. 

Soft and Hard Water — Carbonate of Lime — Sulphates of Lime and Mag- 
nesia — Incrustation — Prevention and Removal of Scale — Kemp's 
Boiler Cleaner — Use of Tannic Acid — Starchy C'ompounds — Car- 
bonate of Soda — Crude Petroleum — Tannate of Soda — External 
Corrosion — Internal Corrosion — Pitting of Plates — Grooving, 

Feed water maybe divided into two distinct classes: 
Fresh and salt; as we have nothing to do with marine 
boilers in this book, the latter will not be considered. 
Fresh water may be either soft or hard. 

By soft water, is meant pure water; that is, water 
which, upon evaporation, leaves no mineral residue which 
had been held in solution. It may contain impurities 
which are held mechanically, such as sand, mud, etc., 
which may also be removed mechanically by filtering, or 
percipitation in tanks where the water is allowed to be- 
come quiescent. The localities in which pure or soft water 
abounds are not numerous. It is the best water for boil- 
ers whenever it is practicable to obtain it. Rain water 
may and often is collected in cisterns for small powers; 
this is quite practicable and is recommended. 

Hard water is to be distingjiished from soft in its con- 
taining in solution salts of lime, magnesia, iron, etc.; the 
two former being by far the most common. There aro 
localities in which the sulphates of lime and magnesia pre- 
dominate, though the carbonates are oftener met with. 



INCRUSTATION. 423 



There are other substances, such as silica, alumina, salt, 
etc., which are often found in feed water. 

Carbonate of lime is well known to us under the names 
of limestone, marble or chalk. Its presence in feed water 
may be accounted for in this way: rain water falling upon 
the surface of the ground is taken up by the soil, and in 
its passage through it absorbs more or less carbonic acid, 
there present as a result of organic decay. Cold water 
dissolves about its own volume of carbonic acid, whatever 
be the density of the gas with which it is in contact; this 
property decreases as the temperature of the water in- 
creases, so that at the boiling point it is scarcely percep- 
tible. 

When water so saturated comes in contact with lime- 
stone or marble it dissolves it and w^e liave wells or springs 
which yield hard water. When this water is heated to the 
boiling point, the carbonic acid is given off and the car- 
bonate of lime remains in the boiler. For a time it is held 
mechanically in suspension, but gradually attaches itself 
to the boiler, forming a soft scale by allowing it to dry to 
the shell after blowing out, the furnace walls being still 
'hot. 

Mr. J. M. Allen says, in his annual report* for 1873: 

"It has generally been supposed that a deposit in a soft state 
caused little or no injury to a boiler; but our experience has proved 
conclusively that the contrary is true. The impalpable powder found 
'in a boiler, when empty and dry, is mainly carbonate- of lime, and on 
account of its lightness it is long held in suspension. When the 
water, from constant evaporation and little or no blowing, becomes sat- 
.urated with this material, it is rendered unfit for generating steam on 
account of the resistance offered to the escape of the steam bubbles, 
and to the free convection of heat. A deposit of slush or sludge col- 
lects on the bottom, around the seams, and in fire box boilers around 
the furnace sheets and in the water legs. ' Its presence is detected by 
leakage at the seams, fractures at the edge of the plates, and in the 

*lliirtford Steam Boiler -Inspection -and Insurance Co., J. M. Allen, President, Hart- 
ford, Conn. 



424 A TREATISE ON STEAM BOILERS. 

line of rivets, and by over heating, and consequent depressions of por- 
tions of the plates where it rests. 

" This action may be better understood by those who have watched 
the process of making what is known as "hasty pudding." As the 
corn meal and water begin to boil the diflficulty which the steam or 
vapor generated at the bottom has in escaping is manifested by the 
sputtering manner in which the surface of the mush is thrown 
about. If vigorous stirring is not kept up, it burns on the bottom, 
and acts very much as the slush or sludge from lime does in steam 
boilers. 

" This difficulty is greatly aggravated if grease finds its way into 
the boilers; the grease appears to combine mechanically with the car- 
bonate of lime and sinks on the plates when the boilers are at rest. 
It becomes a loose, spongy mass, which is not carried off by the circula- 
tion, but, by its contact with the plates, keeps the water from them, 
and, by offering resistance to the free transmission of heat, causes 
over heating and burning of plates. Before we had fully investigated 
this subject, our opinion was, in many instances, where boilers were 
leaking badly and showed indications of having been burned, that it 
was caused by the carelessness of the engineer in starting his fire, 
with no water in the bailer." 

What has been said in resrard to carbonate of lime is 
also in the main true of magnesia. 

Sulphate of lime is known to nearly every one under 
its common name, plaster of paris. It is soluble in nearly 
four hundred parts of water, at a temperature of 95° and 
almost if not completely insoluble at a temperature of 
290°, or slightly more than that corresponding to forty 
pounds steam pressure. When once found in the boiler, 
there is no such thing as re-dissolving it by a mere reduc- 
tion of pressure, as it forms much more rapidly during the 
day by evaporation than the water will re-dissolve during 
the night, should the temperature ever get so low as 95°. 
The formation of scale in a boiler in which sulphate of 
lime predominates is quite irregular; being more than 
twice as heavy as water, it can not long remain in suspen- 
sion, and is found in deposits of varying thickness, the 



INCRUSTATION. 425 



hardness varying according to the substances in combina- 
tion with it, and the heat to which the whole may have 
been subjected; and forms, perhaps, the most troublesome 
scale that the steam user has to contend with. 

Carbonate of magnesia will be found in feed water in 
localities in which magnesian limestone abounds. It is 
not usually found in any great quantity, as compared with 
the other salts named. In its behavior in the boiler, it is 
not unlike carbonate of lime at similar temperatures. 

There are a number of other substances which act in a 
manner analogous to those already referred to, but as they 
are in general so small in quantity, when compared with the 
others, they need not here be particularly described. 

The impurities in feed water, when consisting of salts 
of lime and magnesia, produce incrustation; when an excess 
of acid is contained in the water, corrosion takes place. 

Incrustation, when allowed to form in any boiler, has 
the effect to reduce its steaming capacity and also induces 
over heating of the plates, by reason of its being a non- 
conductor of heat Its presence also prevents a satisfactory 
internial examination of a boiler, as it covers the joints and 
other portions which should be laid bare to make the 
inspection thorough. 

Many attempts have been made to calculate the loss of 
heat by the accumulation of scale. The results show great 
loss, but exactly how much is not entirely known; it is 
placed by different observers as follows : 

^ inch thick requires an increase of 15 per cent in fuel. 

i inch thick requires an increase of 30 to 60 per cent in fuel. 
J inch thick requires an. increase of 60 to 150 per cent in fuel. 

This last line is given for what it is worth. 



426 A TREATISE ON STEAM BOILERS. 

The prevention and removal of incrustation is a subject 
which interests every one having a boiler fed with hard 
water. The usual means of prevention and removal are, 
by blowing off; the use of chemical agencies which render 
the impurities more soluble ; the use of some mechanical 
device, fitted to the interior of the boiler, which will col- 
lect the deposit and which may then be removed, cleaned 
and replaced. 

Blowing off is the easiest and readiest method of get- 
ting rid of surface impurities which will prevent the free 
escape of steam at the surface of the water. There are 
many devices for this purpose; the one described below is 
said to yield excellent results by those who have them in 
use. 

Kemp's boiler cleaner^ as manufactured by James F. 
Hotchkiss, Bay City, Mich., is shown in figure 189, as 
attached to the boiler when in use. 

A is a box or reservoir located above or upon the arch 
wall of the boiler. lu marine boilers the reservoir may be 
suspended from the deck frame above; from this reservoir 
three pipes extend; the first pipe, B, enters the rear part 
of the top sheet of the boiler or generator, and is con- 
nected with a horizontal pipe, which is adjusted a little 
below the water line. At either end of this horizontal 
pipe is an enlarged mouth, C, partly submerged, but 
extending a little above the surface of the water — the 
mouths being of a diameter to allow several inches varia- 
tion in the water line. The second pipe, D, leading from 
the reservoir A, enters the other end of the boiler, in sim- 
ilar manner, terminating below the water surface. 

When the boiler is heated, a constant current of water 
is immediately established through the bell mouth C, and 
pipe B, filling the reservoir A, and, cooling to a certain 
extent, it returns to the boiler by the pipe D. It will be 



KEMP S BOILER CLEANER. 



427 




observed that the up flow pipe is placed about midway 

between the fire bridge and the back end of the boiler, at 

a point where the water is presumably hottest. On the 

other hand, the down flow 

pipe enters the front or 

cooler portion of the water, 

and, while the water may 

rise and fall in the boiler 

to any moderate extent, 

the enlarged mouths, C, 

will constantly maintain a 

current free from steam, 

from the surface. 

As the sediment and 
impurities are chiefly sep- 
arated from the water by figure 189. 
ebullition in that part of the boiler where the horizontal 
pipe C is located, they are immediately drawn in by the 
current and carried into the reservoir A; here, the current, 
weakened by expansion, can support the impurities no 
longer, and they settle in the reservoir, and are retained, 
until blown off* through the third pipe E, as seen in the 
engraving. The reservoir may be located at any desired 
point above the level of the water line, as most conven- 
ient, and occupies no appreciable room. It usually holds 
about three gallons of water. 

When the boiler is in use the stop cocks should always 
be left open. 

To wash the reservoir out, open cock E for about half 
a minute once each day, or as often as necessary. This is 
simply all the attention required in a general way. By 
placing a vessel under the blow off* pipe, the amount of 
deposits can be easily ascertained. 

In severe cold weather, where the boiler is exposed and 
allowed to stand unused a day or more at a time, shut the 



428 A TREATISE ON STEAM BOILERS. 

stop cocks D B, and open cock E, leaving the reservoir 
empty; but so long as the water is warm in the boiler, it 
will circulate through the reservoir and keep it from 
freezing. 

The use of chemical agents seems to be a favorite one for 
the prevention or removal of scale. There are hundreds 
of "boiler compounds," some of them of surpassing excel- 
lence, others perfectly useless, if not positively hurtful. 
Nearly all compounds for this purpose have either tannic 
acid or soda as the active agent. Yegetabie matter does 
not, as a general thing, act injuriously on the plates and if 
it contains any considerable quantity of tannic acid, it may 
prove of great value in arresting or preventing incrusta- 
tion ; and for this reason caoutchouc (crude india rubber) 
nutgalls, logwood^ hemlock, mahogany, etc., are often 
employed as scale preventives. The chemical action of 
the tannic acid is to decompose the carbonates in the 
water, and thus to form a tannate of lime, instead of a car- 
bonate, and in the same manner for carbonate of magnesia. 
Tannates of lime and magnesia are not soluble, and being 
of light specific gravity, are held mechanically in suspen- 
sion by the circulation of the water. These particles of 
tannate of lime or magnesia floating in the water do not 
have a tendency to unite to form masses by their adhesion, 
and may easily be blown out of the boiler with the water. 
This chemical reaction does not occur in water contain- 
ing sulphate of lime, and for this reason an analysis of the 
water should be had before using any compounds having 
tannic acid as the principal ingredient. 

Molasses, potatoes, vinegar, etc., etc., have found their 
way into boilers as preventives. The latter containing 
acetic acid, decomposes the carbonates of lime and mag- 
nesia, forming acetates, which, being soluble, are kept in 
solution and do not form scale. There is danger, however, 



INCRUSTATION. 429 



that an excess of free acid will act injuriously on the 
plates. In regard to potatoes or any starchy compounds, 
they may and often do prove serviceable. Their action 
seems to be mechanical, and to envelope the solid particles 
of lime and prevent adhesion. Scale has not only been 
prevented, but actually removed, by simply using potatoes 
in the boiler. It should be borne in mind that starchy 
ingredients, of whatever kind, have a tendency to produce 
frothing, and thus to deceive the fireman as to the correct 
water level. These have little or no action on sulphate of 
lime, but are to be confined to water having carbonates 
only. 

Carbonate of soda, caustic soda, potash and other fixed 
alkalies have been used with varying results. These will 
decompose sulphate of lime and form sulphates of soda or 
potash, which will be retained in solution and the carbon- 
ate of lime precipitated. 

Alkalies do not injuriously attack the plates of the 
boiler, and may often prove beneficial in neutralizing the 
effect of free acids present in the water. 

Petroleum has been used with marked results. Mr. 
Allen says, in the same report already quoted from, 

"We have a specimen of scale in this office nearly one and a half 
inches thick, that was removed from a boiler in the west by crude 
petroleum, or what is known as unrefined, black, earth oil. 1 am 
aware that there is great prejudice against using anything of the 
kind in steam boilers, but earth oils are very different from animal 
oils. They are very volatile, and in an experience of several years 
where hundreds of boilers have been treated with it, we have found 
no injury to plates or tubes, and the boilers have been kept free from 
scale. Petroleum works better where sulphate of lime predominates, 
than in waters impregnated with carbonate of lime. We would not 
advise it in connection with the latter. I desire to impress upon all 
persons the importance of careful attention to their boilers when sol- 
vents of scale or purgers are used. It often happens that scale is 
thrown off and allowed to accumulate on the bottom of the boiler, 
and from want of attention, not being removed, the boiler becomes 



480 A TREATISE ON STEAM BOILERS, 

burned and nearly or quite ruined. If a purger is used, the boiler 
should be often opened and as often thoroughly cleaned." 

Tannate of soda is a compound which, it is claimed, 
will hold both the carbonate and sulphate of lime in solu- 
tion. This compound was finally decided upon after a 
laborious chemical research, by Jos. G. Rogers, M.D., 
Madison, Ind. Its action may be described thus: Tannate 
of soda decomposes the carbonates of lime and magnesia 
as they enter, tannates being precipitated in a light, floc- 
culent, amorphous form, so that they do not subside at all 
in the boiler, but are retained in suspension by the boiling 
currents until they find their way into the mud receiver, 
where they settle into a loose, mushy mass, 'which may be 
easily blown out from time to time. The carbonate of 
soda, formed in the reaction, is retained in solution, becom- 
ing a bicarbonate by appropriation of the free carbonic 
acid in the water. This decomposes the sulphate of lime, 
the resulting sulphate of soda being retained in solution, 
and the carbonate of lime being acted upon by fresh por- 
tions of the tannate of soda as above. The constant pres- 
ence of the alkali protects the iron from all action, either 
of the carbonic or tannic acids. The same reaction takes 
place between the tannate of soda and the already existing 
scale, with like results, but more slowly, some weeks being 
generally required, in practice, in removing the deposit, if 
it exists in any considerable quantity. 

Zinc has been used with some success with water con- 
taining bicarbonate of lime; it has no eftect on sulphate of 
lime. The disappearance of zinc in the boiler is no indi- 
cation that it is preventing scale, as it may be reduced by 
galvanic action. 

This portion of the chapter might be almost indefin- 
itely extended, and be of no practical use when concluded. 



CORROSION. 431 



The writer has given in brief outline the action of the 
commonest and perhaps the best anti-incrustators. One 
thing must be done before any one of the several substances 
named can be recommended; that is, an analysis of the 
water, showing whether it contains carbonates, sulphates 
or acids, which of each, and in what quantities. Then and 
only then, can an intelligent recommendation be given. 
The writer's advice to boiler owners is that, no preparation 
be bought or used until after such analysis by a competent 
expert or chemist. 

External corrosion is frequently caused by the exposure 
of the shell of the boiler to the weather. It often occurs 
that boilers have no other protection than simply a loose 
board roof which, even in ordinary rain storms, leak at 
every joint. If the boilers were always under steam thei 
bad consequences would be comparatively light, but the 
greater mischief occurs when the boilers are cold. When- 
ever rust appears on the surface of a boiler it means loss 
of iron, loss of strength, and consequently is less able to 
withstand high pressure. The danger is increased if the 
action of the rust be confined to certain portions of the 
boiler and continuous deterioration be going on ; this is 
likely to occur along the line of brick work, in externally 
fired boilers, near the water line. In exposed situations 
this rate of corrosion may amount to one-sixteenth inch 
in a single year. This is perhaps exceptional; but a boiler 
would soon be rendered worthless if only half that waste 
of iron was going on and which is not at all exceptional. 

Another source of corrosion is that which proceeds 
from leaky joints, either from the riveted seams, man or 
hand holes, or from imperfectly fitted attachments. When 
the leak occurs around a rivet a new one should be put in ; 
if in the seam, it should be re-calked inside and out. The 
gaskets used between the shell and hand, or man hole 



432 



A TREATISE ON STEAM BOILERS. 



plates, are often so imperfectly fitted that it is the excep- 
tion to find them perfectly tight. A gasket of vulcanized 
rubber, say three-sixteenths to one-fourth inch thick, is 
recommended rather than a plaited one made of hemp, 
when used with high pressures. A gasket recently 

brought to the attention of the 
writer is shown in figure 190, and 
is the invention of Mr. C. S. Stoy, 
Butler, Indiana. It consists of a 
thin copper shell, filled with pack- 
ing, as shown. There is little doubt 
that it will make an excellent joint 
and may be used over and over again. 
But whatever packing may be used 
the joint must be tight, and a leak, 
however trivial around a boiler, 
FiiiUKK lyo. should be immediately repaired. 




Internal corrosion — This wasting of the plates is doubt- 
less caused, in the main, by the action of acids in the 
water. It has also been attributed to galvanic action. A 
noticeable thing in connection with internal corrosion is 
its want of uniformity; its appearance is not unlike ordi- 
nary rusting and is not difficult to detect. The following 
extract is from Mr. Allen's report for 1875, and agrees 
with the writer's own observations. I am also indebted to 
Mr. Allen for the accompanying engravings: 

"The work of corrosion is insidious, whether it is external or 
internal. A boiler that is set in brick work may leak at the seams, 
and corrode the plates adjoining, and yet there may be no indication 
of danger. So, by the use of impure water, a very dangerous process 
may be going on inside the boiler. 1 n boilers covered more or less 
with scale its presence is often detected by red streaks where the 
scale is cracked. It attacks the edges of plates at the joints, and 
around the rivet heads. Sometimes it will attack two boilers working 
side by side. One will be corroded in the front part, and the other 



I 



CORROSION. 



433 



in the back part. Sometiraes different sheets in the same boiler will 
be corroded, while others remain intact. Again, boilers will be found 
in what is known as a pitted condition. This is manifested by small 
spots in close contact, being eaten into the sheet. It looks like a^ 
pock marked face and is sometimes confluent; and what is strange 
about this is, that often certain sheets in the boiler will be attacked 
while others will remain clean and smooth, and the iron will bear the 






-^s^sNvNNv .- --^^^^^^ \.. "":"2i 



Figure 191. Section on A B. 

same brand on each plate. It is well known that iron ore, even from 
the same mine, is not always chemically the same; certain impurities 
will be found in some places which do not exist in others. And in 
the manufacture of boiler iron there is no doubt but that the sheets 
are chemically slightly different; hence, when the boiler is constructed 
the presence of acids in water may excite galvanic action. This would 
account for the different manner in which boilers are affected. The 
following figure will illustrate the effects of corrosion: 

"This was discovered by inspection. The outer and inner side of 
the sheet is shown in the drawing ; also a cross section. The hole in 
the center of the sheet was made by the inspector's chisel. The iron 
was little thicker than paper ; the piece of plate can be seen in this 
office. 

(29) 



434 



A TREATISE ON STEAM BOILERS. 



Figure 192 represents a portion of the inner plate of a water 
leg of a locomotive boiler. Corrosion attacked the plate around the 
stay bolts, as represented by the radiating dark lines. The other end 
of the stay bolts' was eaten nearly off. We judge from appearances 
that in tapping out the holes for the stay bolts, a strain was brought 
to bear which disturbed, the fiber of the iron, or perhaps I should say 
the skin of the iron ; imperceptibly, however, to the casual observer. 





Figure 192. 

"The difficulty was further aggravated by the unequal expansion 
and contraction of the two sides of the water leg. The inner sheet 
forming the side of the fire box was subjected to greater heat, and this 
continual, though imperceptible action assisted in increasing the 
difficulty. 

" Impure water found this disturbed point the most open to attack, 
and the result is as we find it here. The furrows are eaten in quite 
deep, and it looks like the work of a tool." 



Pitting — When internal corrosion occurs in isolated 
spots it is called pitting. This generally occurs near the 
joints of the plates, but not unfrequently directly on their 
faces. It is not uncommon to find pitting up in the steam 
dome, and from the fact that it is as likely to occur away 
from as in contact with the water, it is now generally 
believed to be due to galvanic action. 



GROOVING. 



435 



Figure 193 is loaned by Mr. Allen to show the peculiar 
corrosive effects found in a boiler fed by swamp ivater, and 
is engraved from a sample now in the office of the Hart- 
ford Steam Boiler Insurance and Inspection Company. 

Gi'ooving— There is not a well defined and satisfactory 
explanation which will wholly account for this destructive 




Figure 193. 

action in boilers. It is believed, however, that it is caused 
by the constant changes of form which take place in a 
boiler by the alterations of pressure, and thus induce a 
hinging or buckling action of the plates, particularly along 
the lines of riveted joints. In the ordinary method of 
making boilers, it is impossible to make a shell perfectly 
round, and when such a boiler is subjected to steam pres- 
sure the tendency is to make it a true cylinder, and this is 
the cause of the buckling or hinging above referred to. 
If the plates are made of fibrous iron, they are loosened 
every time this occurs, and it is greatly aggravated by the 



436 A TREATISE ON STEAM BOILERS. 

continued changes of temperature to which the whole is 
exposed. The iron being less firm at this point than else- 
where, corrosion becomes all the more easy and certain, 
and is further assisted by imperfect or too rigid bracing at 
certain points, and too slack at others. It is not now, as 
was formerly, believed to be due to galvanic action. 



CHAPTER XVI I. 



SECTIONAL BOILERS. 

The Babcock & Wilcox Boiler— The Boot Boiler— Kelley's Boiler— The 
Firmenich Boiler. 

Sectional boilers are not as yet common property, and 
the writer can only refer in a general way to the details of 
construction as practiced by the several makers, whose 
idesigns may be described. No attempt can be made in a 
single chapter to trace the development of sectional boilers, 
nor to describe all those now in the market ; three or four 
examples will be given to illustrate the present practice of 
the leading manufacturers. 

The Babcock Sf Wilcox boiler is shown in front elevation 
in figure 194, in longitudinal sectional elevation in figure 
195, and in cross sectional elevation in figure 196 ; these 
three engravings, for convenience of reference, are printed 
on the same sheet. 

This boiler is composed principally of lap welded 
w^rought iron tubes four inches in diameter, arranged in 
sections, having seven or eight tubes in each. These sec- 
jblons are inclined at an angle of about 15°, as shown in the 
sectional elevation. 

These sections are connected with each other, and with 
a horizontal mud drum at the bottom, and rear of the 
boiler, and also by vertical passages at each end, with the 
two horizontal steam and water drums shown in the cross 
sectional elevation. The water fills all the tubes and 
extends half way up and into the steam and water drums. 




THE BABCOCK & WILCOX BOILER. 

FlQURE 196. 



438 TREATISE ON STEAM BOILERS. 

The end connections are in one piece for each vertical 
row of tubes ; these tubes do not lie one above the other 
in a vertical line, but are staggered so as to receive heat 
either by radiation or direct impact by the flow of heated 
gases upwards through the spaces between them. These 
tubes are not threaded, but secured to the end connections 
by the use of an expander in a manner similar to that in 
which tubes are fixed in an ordinary tubular boiler. The 
connections between the mud drum and the steam and 
water drum are made in the same manner, and thus dis- 
pensing entirely with bolted joints and packing. By this 
arrangei;nent are secured freedom from strains induced 
by unequal expansion, and a means of rapid and thorough 
circulation of water. The water inside of the tubes when 
heated has a tendency to rise toward the higher end, and 
flows upward and into the steam and water drum. The 
steam is here given ofi*, if the water is of suflSciently high 
temperature. The back connection secures a downward 
current, and thus a continuous circulation is established, 
preventing the evils arising from the destructive strains 
consequent upon unequal temperatures. This rapid circu- 
lation also prevents, in a measure, the formation of scale 
upon the heating surfaces, sweeping the particles away 
and depositing them in the mud drum, from which they 
may be blown out. 

The provision for cleaning the boiler, both internally 
and externally, is quite complete. Hand holes opposite 
each end of each tube, man holes in the drums, and a bon- 
net to the mud drum, permit access to all parts of the inte- 
rior, while side doors admit of the removal of accumulated 
dust and ashes from the exterior of the heating surfaces, 
either by blowing, brushing, or any other well known 
means. 

The proportions of this boiler were adopted after 
numerous experiments with boilers of varying capacity; 



BABCOCK & WILCOX BOILER. 439 

and experience has established that it can be driven to the 
utmost, and still be free from the objections always attach- 
ing to boilers of small capacity — carrying a steady water 
level and steam pressure, and always furnishing dry steam. 

The cubical capacity of this boiler, per horse power, is 
equal to that of the best practice in tubular boilers of the 
ordinary construction. The fire surface being of the most 
eft'ective character, these boilers will, with good fuel and 
a reasonably economical engine, greatly exceed their 
nominal power, though it is seldom economy to work a 
boiler above its nominal power. The space occupied by 
this boiler and setting is equal to about two-thirds that 
of the same power in tubular boilers. 

The following is an abstract of a test of a Babcock & 
Wilcox boiler, by Charles E. Emery, C.E., l^ew York city. 

This test was made in February, 1879, at the Raritan 
Woolen Mills, Earitan, E". J. There were two boilers in 
use, containing 4,080 square feet of heating surface, and 
103 square feet of grate surface, the capacity of the two 
boilers being rated jointly, by the makers, at 360 H.P. 

The experiment commenced at 6.01 a. m., and closed at 
6.38 p. M. In starting, steam was raised by spreading the 
banked fires left from the previous day. When the pres- 
sure reached 80 pounds the fire was hauled, all refuse 
removed, and fires started anew with wood, which in the cal- 
culation has been considered equal in calorific value to -^ 
its weight of coal. The fires were maintained with coal 
during the day, finally hauled, allowed to cool, the com- 
bustible portion deducted from the coal charged, and the 
refuse weighed separately. The experiment was closed 
when the boilers stopped making steam at 80 pounds 
pressure, with water in the glass gauges at same height as 
at starting. 

During the trial, all the coal consumed was weighed in 
an iron wheelbarrow, balanced when empty by a fixed 



440 A TREATISE ON STEAM BOILERS. 

weight, and each barrow load was adjusted at the scale to 
weigh 200 pounds net. All the water evaporated was 
measured in a tank provided with a heavy float connected 
through a fine chain to an index showing the water level 
on an exterior scale, divided decimally. By weighing 
water out of the tank, its capacity was found to be 5,172 
pounds of water between the limits employed. 

A complete record was kept of the coal, water, steam 
pressure and various temperatures, and the quality of the 
steam was tested with a calorimeter at frequent intervals. 
The proprietors of the mill took the proper business pre- 
caution of stationing observers at each point, who kept 
entirely independent records, agreeing with those taken by 
the assistants. The coal used was clean nut coal from the 
Lackawanna region. It had been exposed to the weather 
during the winter, and when first taken from the pile was 
wet, but a sufiacient quantity for the trial was brought 
under shelter a few days in advance, so that the coal 
actually used was bright and appeared dry. The results 
of the trial are as follows : 

Average steam pressure 71.63 

Average temperature of fire room 44.00 

Average temperature of water in feed tank 90.47 

Average temperature of water entering boiler after passing through 

a heater in flue 110.59 

Average temperature of up-take boiler No. 1 by pyrometer (evidently 

wrong) 381.87 

Average temperature of flue beyond feed water heater 453.23 

Wood used in starting fires, 750 pounds, equivalent of coal 

(730x .4) 292 pounds. 

Coal put in furnaces during experiment 19,827 pounds. 

Total of above 20,119 pounds. 

Combustible in refuse at close of experiment 820 pounds. 

Total coal consumed, including equivalent of wood 19,299 pounds. 

Refuse from coal removed during experiment 749 pounds. 

Refuse from coal at close of experiment 2,134 pounds. 

Total 2,883 pounds. 

Actual percentage of refuse (2.883 -^ 19,299 x 100= ) 14.94 per cent. 

Combustible consumed (19,299—2,883=) 16,416 pounds. 

Coal Avith 12 per cent refuse agreed upon equivalent to that 

actually consumed [16,416-^ (100—12) = ] 18,654.5 pounds." 



THE ROOT BOILER. 441 



Total weight of water actually evaporated at i)ressure of 

71. C3 pounds from temperature 110.59° 101,573.28 pounds. 

Equivalent evaporation at pressure of 70 pounds from 

temperature of 180^, as agreed upon 172,592.58 pounds. 

Evaporation per pound of coal, with 12 per cent of refuse, at 

presureof 70 pounds, from temperature of 180^ 9.252 pounds. 

Evaporation per pound of combustible, atmospheric pres- 
sure from temperature of 212^^ 11,221 pounds. 

On the basis that ain^ good engine, under fair condi- 
tions, will require hut 30 pounds of water per hour for 
horse power, these boilers developed 464 H. P., or 104 
horse power in excess of that required bj the contract. 

7^he Root boiler manufactured by the Abendroth & 
Root Manufacturing Company, Brooklyn, New York, is 
shown in sectional elevation in figure 197, and in front 
elevation in figure 198. By reference to the engravings 
the construction of this boiler will readily be understood. 
The tubes are four inches in diameter and inclined as 
shown in the sectional elevation. These tubes are 
screwed into cast iron caps as shown in figure 199, 
in which A is the tube, B the B^^ 

cap and E a stud by which a [ B J ^--' — x c,^ x x.~xx. <^^ ^ 

triangular elbow is held in nitl^^Tl r__^^^ - - -- ^ 
place; this elbow is shown in ^ ^J|^^S^:^^^^^ 
elevation in fie^ure 201, and in w^mmzSa'^ — ^^--- --..v,,^^ 

partial section in figure 200. figure 199. 

It will be observed that each tube screws into a square 
end cap in which are three openings. These caps are 
exactly alike, except those in the lower row, which 
differ in size and require a modified elbow connection, as 
is clearly shown in the sectional eleva- 
tion. The manner of securing the trian- 
gular elbow J) is shown in the enlarged 
FIGURE 200. engraving, figure 201. The object of this 

square end cap and triangular elbow is to permit a free 
circulation of water through and exit of steam from the 




442 



A TREATISE ON iSTEAM BOILERS. 



tubes. The steam is collected from the tubes into the 
steam drum S, which is placed over the top of the boiler, 
as shown. This form of construction afiords ready facility 
for cleaning or renewal of tubes. 

The water should not be carried too high if there is a 
severe drain on the boiler, as it is likely to induce priming. 
When steam is generated in the tubes, it rises to the 
steam drum through the triangular elbows (return bends 
would perhaps be nearer correct), seen at the front end of 

the boiler. In pass- 
ing; throu2:h the 
bends the current 
is broken, and if 
any water is min- 
0^1 ed with the steam 
it is thrown back 
into each tube. 

This breaking 
and reversal of the 
current to prevent 
priming is now gen- 
erally recognized as 
the correct way to do it, and no doubt is the explanation 
of the remarkable freedom which this boiler has from this 
troublesome and dangerous occurrence. 

If the demand upon the boiler is constant, a steam 
drum need not be supplied, but when the requirements 
are irregular, it is then perhaps best to have it. 

The grates may be of any of the common or oscillat- 
ing varieties now in the market. 

The course of the products of combustion are clearly 
shown by the' direction of the arrows. The tubes have 
what the makers call '' bridge wall blocks," which are 
shown at A. These are built up to any required height, 




FiGUKK 201. 



,*f 









THE ROOT BOILER. Sectional Elevation. 
Figure 197. 




THE ROOT BOILER. Front Elevation. 
Figure 198. 



11 



kelley's sectional boiler. 44B 

to insure every part of the tubes being in contact with 
the heated gases. 

The following test was made at the Centennial Exhi- 
bition, Philadelphia, Pa. : 

Heating surface, square feet 1,590. 

Grate surface, square feet 42. 

Coal used (anthracite), pounds 3,053.9 

Ashes, pounds 320.2 

Steam pressure, pounds 69.94 

Temperature of feed water, degrees 64. 59 

Water evaporated by calorimiter tests, pounds 27,146.69 

Water evaporated per one pound of coal from tem- 
perature of feed, in pounds 8.89 

Water evaporated per one pound of coal from and 

at 212°, pounds 10.35 

Water evaporated per one pound of combustible 

from temperature of feed, pounds 9.93 

Water evaported per one poured of combustible 

from and at 2 1 2°, pounds 11. 565 

Water evaporated per square feet of heating surface 

from temperature of feed, pounds 2.22 

Water evaporated per square feet of heating surface 

from and at 212°, pounds 2.48 

Kelley's sectional boiler, by William E. Kelley, New 
Brunswick, E". J., is shown in sectional elevation in figure 
203, and in detail showing the manner of securing the 
tubes and the circulation of the water through the boiler, 
in figure 202. 

The tubes in this boiler are 3 inches in diameter, and 
screwed into the vertical chamber, as shown in the detailed 
engraving. 

These tubes, with the exception of those in the upper 
row, are inclined at an angle of about one to eight, and 
connected at one end only, and that at the vertical chamber. 

The tubes are therefore left free to expand separately 
without afiecting others, and in like manner may be removed 
for examination or repair. A cap is placed at the back 



444 



A TREATISE ON STEAM BOILERS. 



end to close each tube. Inside of these tubes are placed 
partition plates, as also shown. 

The inclined tubes are always full of water, the water 
line of the boiler being at W. L. The heat from the fuel 




Figure 202. 



on the grate in rising first comes in contact with the lower 
half of the inclined tube, the upper half of the tube being 
in a measure shielded or protected from the direct heat or 
flame by the lower half; consequently tjie greatest amount 
of steam will be generated from the surface of the lower 
half of the tube. The steam thus made would rise to the 
upper side of the tube, were it not intercepted by the par- 




THE KELLEY SECTIONAL BOILER. 

FIGURE 203. 



kellby's sectional boiler. 446 

tition plate; this causes the steam to move along the under 
side of the partition plate, and along the outside of the 
pocket in the front chamber, and thence into the dome, 
first passing through the horizontal pipe, as will be here- 
after explained. The upper half of the tube, as before 
stated, will be less exposed to the direct action of the fire; 
hence the water will flow down the coolest part of the 
tube, and through an opening, D, in the rear end of the 
partition plate, and thence up through the lower half of 
the tube, as before stated, the circulation being accelerated 
by the volume of steam that is seeking an exit from the 
lower half of the tube into the front chamber. The pockets 
in the front chamber tend to keep the downward and 
upward currents separate. The arrows on the cut indi- 
cate the direction of the circulation. 

The free exit of the steam from the front chamber into 
the dome is obstructed by a partition running entirely 
across the chamber, near the top and above the water line, 
W. L., and the steam is compelled to pass along under the 
partition in the horizontal pipe, and through the opening 
in said partition, and then along over it, through the upper 
half of the tube into the chamber and dome ; as the tubes 
are in the heat and above the water line, the steam is made 
very dry, and all moisture and water that would otherwise 
be carried out of the boiler is converted into steam in 
passing through the horizontal tubes. 

The following test was made at Philadelphia, during 
the Centennial Exhibition : 

Heating surface, square feet 662. 

Grate surface, square feet 27.5 

Coal used, anthracite, pounds 2,380.95 

A shes , pounds 204. 5 

Steam pressure, pounds 69.95 

Temperature of feed water, degrees 66.95 

Water evaporated by corrected calorimiter tests, 

pounds 18,710.53 



446 A TREATISE ON STEAM BOILEKS. 

Water evaporated per one pound of coal from 

temperature of feed, pounds 7.858 

Water evaporated per one pound of coal from and 

at 212°, pounds. 9.139 

Water evaporated per one pound of combustible 

from temjDerature of feed, pounds 8.636 

Water evaporated per one pound of combustible 

from and at 212°, pounds 10.94 

Water evaporated per square foot of heating sur- 
face from temperature of feed, pounds 3.52 

Water evaporated per square foot of heating sur- 
face from and at 212°, pounds 4.13 

The Firmenich boiler^ by J. Gr. & F. Firmenicli, Buf- 
falo, l!^. Y., is shown in sectional elevation in figure 204. 

This boiler consists of two partially cylindrical wrought 
iron shells at the bottom, separated sufficiently to admit 
the requisite width of grate. From the upper and flat 
side of these lower cylinders or mud drums, pipes extend 
upward and are connected to similar drums at the top. 

Surmounting these two upper drums is still another, 
having suitable connections with the two lower ones, and 
acts as the steam drum or reservoir for the boiler. 

The lower drums vary in size from twelve to twenty- 
four inches, and the upper steam and water drums, from 
twenty to thirty-six inches diameter; the lengths varying 
according to the size of the boiler. The vertically inclined 
heating tubes are from two to three inches in diameter, 
the latter size being used in all boilers over twenty-five 
horse power. This boiler offers good facilities for exter- 
nal and internal examination. Figure 204 is a cross sec- 
tional elevation, showing the arrangement of drums and 
tubes. 

The following figures are taken from the report of the 
economy trials at Philadelphia during the Centennial 
Exhibition: 



THE FIRMENICH POILEH, 



447 



Heating surface, square feet 1,078-88 

Grate surface, square feet 15.84 

Coal used (anthracite), pounds 1,482.35 

Ashes, pound? 153.25 

Steam pressure, pounds 70.06 

Temperature of feed water, degrees.. GS.94 
Water evaporated, calorimiter tests, 

pounds 13,23;^. 6 

Water evaporated per one pound of 

coal from temperature of feed, in 

pounds 8.93 

Water evaporated per one pound of 

coal from and at 212°, pounds 10.34 

Water evaporated per one pound of 

combustible from temperature 

of feed, pounds 9 95 

Water evaporated per one pound of 

combustible from and at 212°, 

pounds 11.53 

Water evaporated per square feet of 

heating surface from temperature 

of feed, pounds 1.33 

Water evaporated per square feet of 

heating surface from and at 212°, 

pounds 1.775 

The tubes in this boiler 
being nearly vertical, pre- 
vents the accumulation of soot 
or ashes on them. 

The combustion chamber 
is of unusual dimensions, and 
bj properly arranging for the 
admission of air the combus- 
tion should be complete and a 
very high temperature main- 
tained at all times. 

Those who have this boiler fjgurk 204. 

in use, speak well of it and claim a saving in fuel over 
same evaporation with ordinary boilers. 




the 



INDEX, 



PAGE 

Abbott & Co 260 

Abendroth & Root 441 

Absorption of heat 187 

Acetic acid in boilers 428 

Acids in feed water 432 

Action of fire on plates 141 

Adatnson, D., on Bessemer steel 49 

Adam son, D., on Siemens-Martin steel.. 64 

Adamson's joint for flues 260 

Addition to factor of safety 152 

Advantages of steel for boilers 30 

Air forcing apparatus 326 

Air required for grate surface 315 

Air, resistance of through pipes 315 

Air-space boiler covering 391 

Albright & Stroh 309 

Allen, William & Sons 383 

Alumina in water 423 

American boiler plate, strength of 17, 68 

American Linen Co 320 

American Steam Gauge Co 407 

Analysis of Bessemer steel 50 

Analysis of crucible steel 41 

Analysis of iron plate 16 

Analysis of open-hearth steel 57 

Analysis of Workington iron 57 

Annealing 143 

Annealing after punching 106, 109 

Annealing east iron 12 

Annealing flanged heads 139 

Annealing thick steel plates 107 

Anti-incrustators * 431 

Arching back connections 308 

Area, reduction of by tests 77 

Areas of lap-welded tubes 247 

Area of tubes for vertical boilers 276 

Asbestos covering BSO 

Ashcroft, E. H 2o4 

Ashcroft safety valve 399 

Atkinson, George H 23 

Atlas Engine Works 296 

Automatic boiler feeder 309 

Auxiliary pumps 350 

Babcock & Wilcox boiler.... 437 

Babcock & Wilcox economizer 388 

Back plates 308 

Baffle plates 282 

Baxter boiler 274 

Bead on the ends of tubes 177 

Bending of joints under stresa 102 

Bending tests 66 

Bending wrought iron 21 

Bertram's experiments, riveted joints.... 96 



PAGE 

Bessemer pig analysis 45 

Bessemer steel 43 

Bessemer steel analysis 49 

Bessemer steel blooms, tests of 50 

Bessemer steel boiler plates 46, 51 

Bessemer steel, elastic limit of 80 

Bessemer steel, limit to T. S 68 

Bessemer steel rivets .' 120 

Best iron, strength of 67 

Bituminous coal, rate of combustion 247 

Blast gates 314 

Blast nozzle 312 

Blast pipes, sizes for 315 

Blisters in wrought iron 141 

Blow holes in castings 11 

Board of Trade, English 151 

Boiler feeder, requirements of 340 

Boiler rests 308 

Boiler setting 304 

Borden Cumberland coal 320 

Borntraeger, H. W 51 

Bourdon's pressure gauge.... 406 

Bowling iron 69 

Boyd, William 106 

Bracing cast iron boilers 14 

Bradley's crown iron 69 

Breaking and tearing samples 72 

Breaking strain vs. quality 84 

Brittle boilerplates 17 

Brittle iron, punching of 92 

Brown, Aug, P 419 

Brown's iron and steel (.Eng.) 97 

Bulging tests 81 

Bulging tests of steel 55 

Burning steel 119 

Butman, T. R ^^20 

Butt joints, strength of 103 

Cadman, A. W. & Co 419 

Calking 125 

Calking chisel 125 

Calking, Connery's 126 

Calking flues in place 132 

Calking, grooving caused by 130 

Calking tool for tubes 179 

Cambria Iron Co 221 

Camel back boilers 302 

Cammel's iron and steel 97 

Caoutchouc for scale 428 

Carbon in boiler steel 30 

Carbon in castings 10 

Carbon in iron 5 

("arbon in steel 38, 53 

Carbonate of magnesia 425 



INDEX. 



449 



PAGE 

Carbonate of soda for scale 429 

Carbonic acid gas and iron 134 

Carbonic oxide gas andiron 134 

Castings not uniform 9 

Castings, qualitj' of 12 

Cast iron, corrosion of.. 8 

Cast iron, elastic limit of 11 

Cast iron, factor of safety in 11 

Cast iron, flaws in 9 

Cast iron for boilers 8 

Cast iron, how affected by heat 142 

Cast iron, strength of 11 

Caustic soda for scale 429 

Chain and zigzag riveting 109 

Chain joints, strength of Ill 

Chalmeis-Spence Co 391 

Channeling by calking 128 

Chandler & Taylor 238 

Charcoal plate irons 22 

Chemical removal of scale 428 . 

Chilled iron 7 

Chimney draft 312 

Chipping seams 126 

Chipping the ends of tubes 177 

C. H. No. 1 iron 22 

C— iron 22 

Cinder in boilerplates 142 

Cinder in homogeneous iron 27 

Cinder in wrought iron 20 

Cinder prevents welding 134 

Circulating generator. Steads' 384 

Circulation and convection 213 

Circulation and locating tubes 241 

Circulation in boilers 370 

Circulation in economizers 388 

Circulation in vertical boilers 283 

Circulation of water 212 

Classitication of wrought iron 19 

Cleaning fires 309 

Clearance in punch and die 90 

Concave calking 126 

Coal required per hour 246 

Cohesion of iron affected by heat 140 

Coil heater 375 

Cold feed water, injury by 370 

Cold forge tests of steel 55 

Cold punched nuts 90 

Coldshort iron 10, 16 

Collapse of boiler flues 132 

Collapsing pressure 168 

Color heat 144 

Colts' Patent Fire Arms Manufacturing 

Co 274 

Combined safety and stop valve 397 

Compound tubular boiler 254 

Compressing steel ingots ,.,, 34 

(80) 



PAGE 

Compression gauge cocks 418 

Conducting power of metals I89 

Conduction 189 

Conduction of heat by liquids 190 

Conduction, resistance to 196 

Connery, J. W 126 

Consett, Best Best iron 69 

Consolidated Safety Valve Co 399 

Construction of boilers 2 

Contraction of area in samples 85 

Contraction of area recommended 78 

Contraction, strains produced by 371 

Convection 186 

Convection and circulation 213 

Convection of heat.., 190 

Cooling strains in cast iron 9, 11 

Cope & Maxwell 344 

Copper 2 

Copper boilers 196 

Copper in steel 37 

Copper, transmission of heat through.... 196 

Cornish boilers 257 

Cornish boilers, H. P. of 211 

Corrosion 132 

Corrosion, external 431 

Corrosion, how detected 432 

Corrosion induced by strains 443 

Corrosion, internal 432 

Corrosion, rate of 431 

Covering boilers and pipes 389 

Cracking of plates 141 

Crosby's safety valve 400 

Crucible steel, limit to T. S 68 

Crucible steel plates 39 

Crown bars 174 

Crown sheet 174, 191 

Cunningham, G. W 330 

Cylinder boilers 219 

Cylinder boilers, circulation in 214 

( lylinder boilers, H P. of 211 

Cylinder boilers, setting 220 

Damper 220 

Damper, partial closing of 311 

Dangerous connections 396 

Darling, Brown & Sharpe 75 

Dayton cam pump 341 

Dean Brothers 348 

DeBruner, H. G 41 

Decay of tubes 279 

Deep well pump 346 

Defective joints 122 

Defects in iron plates 21 

Defects in large tubes 132 

Defects in .steel plates 32 

Diameter of stay bolts 175 

Diaphragm pressure gauges 408 



450 



INDEX. 



PAGE 

Diffusion of heat in water 213 

Direct transfer of heat 195 

Domes for boilers 180 

Domes, proportions for 182 

Double riveted lap joints 96 

Double riveting recommended 158 

Double riveting, table of 126 

Double walls for furnaces 307 

Douglas & Sons 222 

Douglas, W. B 339 

Draft, forced 312 

Draught circulation 215 

Drifting tests 49, 67 

Drilled and punched holes 87, 105, 1('7 

Dry steam 241 

Ductility and tenacity 18, 34, 78 

Ductility in steel plates 33 

Dudgeon's tube expander 179 

Dutch government, limit to T. S 70 

Economizers 386 

Economizers and boilers 387 

Economizer, Babcock & Wilcox 388 

Economizer, circulation in 388 

Economizer, functions of 387 

Economizer tubes, cast iron 389 

Economy in double riveting 124 

Edgar Thompson Steel Works. 49 

Bdson, M.B 413 

Effect of heat on cast iron 142 

Elasticity 79 

Elasticity and elongation 109 

Elasticity in steel plates 106 

Elastic limit 79 

Elastic limit of Bessemer steel 80 

Elastic limit of cast iron.. 11 

Elastic limit of wrought iron 80 

Elephant boiler ..: 223 

Elongation, percentage of 72 

Elongation tests 76 

Emery, Charles E 439 

Emission of radiantheat 187 

English boiler plate 96 

English government tests for iron 83 

Equalizing diameter of pipes 316 

Equivalent evaporation 204 

Essen and Yorkshire plates 78 

Evaporation 203 

Evaporation, factors of 207 

Evaporation in Cornish boilers 259 

Evaporation in flue boilers 237 

Evaporation modified by heating surface 195 

Evaporation per horse power.. 210 

Evaporation trials, fire box boilers.. 294 

Evaporative capacity, portable boilers..., 297 

Evaporative efficiency 197 

Expander, Dudgeon's 179 



PAGE 

Expander, Prosser's 177 

Expansion of large flues 260 

External corrosion 431 

External heating surface 191 

Externally fired boilers 218 

Extent of heating surface 198 

Eyth, Max 97 

Factor of safety 149 

Factor of safety, additions to 152 

Factor of safety, cast iron 11 

Factors of evaporation 207 

Fairbairn & Hetheriugton 260 

Fairbairn's boiler 265 

Fairbairn on riveted joints ; 95 

Fan blowers 314 

Farnley iron 69 

Faults in steel plates 36 

Faults of steel rivets 119 

Feed apparatus 337 

Feeding water into steam room 322 

Feed water and cast iron 8 

Feed water, heating 375 

Feed water, point of admission 370 

Fernald, F. L 55 

Fibrous and granular iron 20 

Fibrous iron changed to granular 141 

Fire, action of on plates 141 

Fire box, copper 196 

Firebox heating surface 278 

Fire box, high 276 

Firebox iron 26, 161 

Fire box in vertical boilers 272 

Fire box, large or small 279 

Fire clay to be used 308 

Fire door rings 271 

Fire, for heating steel 119 

Firmenich, J. G. & F 446 

Fitting domes to boilers 181 

Five-flue boilers 229 

Flanged work to be annealed 139 

Flange iron 24, 161 

Flanging 139 

Flanging heads 232 

Flanging tests, steel 56 

Flanging wrought iron 21 

Flat surfaces, staying of 175 

Flexure ••. 21 

Flue boilers 226 

Flue boilers, proportions for vertical 271 

Flue boilers, setting 305 

Flue boilers, tests of 236 

Flue boilers, 6 inch 232 

Flue boilers, vertical ^ 270 

Flue heating surface 192 

Flue in Cornish boilers 259 

Flues acting as stays.. 176 



INDEX. 



451 



PAGE 

Flues, diameter of 226, 230 

Flues of large diameter 259 

Flues, securing to heads 176 

Flues, strength of 229 

Flues, strengthening 171 

Flues, thicknessof 171, 229 

Flues, riveting to heads 233 

Flynn, Daniel 286 

Fly wheel pump 348 

Force draft 312 

Forging boiler shells 138 

Forge tests 60, 83 

Formulas for riveted joints 123 

Foundations to be brick 308 

Foot valves 339 

Four inch tubular boilers 252 

Fractured area and T. S 59 

Fractures by punching steel 109 

Fractures in cast iron 11 

Fractures in steel plates 33, 36 

Franklin Institute experiments 145 

French admiralty test specimens 73 

French boiler 223 

Frictional resistance riveted joints 119 

Fuel for vertical boilers 277 

Fuel saved by heating feed 375 

Furnace design 304 

Furnace door, Butman's 329 

Fusible plugs 420 

Gain by heating feed water 374 

Galloway boiler 267 

Galloway boiler, circulation in 215 

Galloway tubes 268 

Galloway, W. & J 185 

Gases, action of heated 194 

Gases, flow of in boilers 192 

Gas furnace 136 

Gaskets 432 

Gauge cocks 418 

Gauge, pressure 405 

Gauge, water 419 

Generator, Stead's 384 

Giflfard, M 352 

Glasgow Best Best iron 69 

Grade of iron for boilers 67 

Granular and fibrous iron 20 

Graphite 7 

Grate area 202 

Grate area and safety valves 394 

Grate area for tubular boilers 246 

Grate area in vertical boilers 277 

Grate and tube areas 239, 249 

Grate bars 309 

Grate bars, Butman's 331 

Grate bars in Suiter's boiler 290 

Grates, distance from boiler 307 



PAGE 

Grates, length of 248 

Grate and heating surface 211 

Gray cast iron 6 

Green's feed water heater 380 

Greig, David 97 

Grooving 435 

Grooving of plates by calking 130 

Hancock, John T 361 

Hancock's inspirator 361 

Hand and machine flanging 140 

Hand holes in boilers 270 

Hand hole plates 241 

Hand riveting, tests of 117 

Hard iron or steel, strength of 77 

Hardening of plates 143 

Hard water 422 

Harrison boiler 13 

Heads, flanging of 232 

Heads for portable boilers 296 

Heads, staying of 176 

Heads, thickness of 242 

Heat, conduction of 190 

Heat, effects of on cast iron 12, 142 

Heat, rate of transmission 208 

Heat, reclaiming from exhaust 874 

Heat, transferof 186, 195 

Heat, transmission of 196 

Heater, coil 375 

Heater and boiler feeder 369 

Heater and economizers 374 

Heater, Green's 380 

Heater, Stilwell's 376 

Heater, Victor 383 

Heating and cooling plates 74 

Heating and grate surface 211 

Heating feed water, gain by 374 

Heating steel rivets 119 

Heating surface 191 

Heating surface and evaporation 195 

Heating surface, extent of 198 

Heating surface in fire box... 278 

Heating surface in flue boilers 227, 231 

Heating surface in flues 192, 201 

Heating surface, position of 192 

Heating surface in shell 199 

Heating surface in tubes 200 

Heating surface in vertical boilers 276 

Height of fireboxes 272 

Hemlock for scale 428 

Herrick, J. A 57 

High fireboxes 276 

High grade iron 161 

Hill, John W 292 

Hoadley, J. C 293 

Holes, conical when punched 89 

Holes leading into domes 181 



452 



INBEX. 



PAGE 

Holley, A. L 221 

Holmes, Isaac V 235 

Holt, John P : 409 

Homogeneous iron 27 

Homogeneous plates, properties of 35 

Homogeneous plates, stretch of 72 

Hoopes & Townsend 90 

Horse power of boilers 209, 238, 277, 278 

Hotchkiss, James F 426 

Hot-short iron 10, 17 

Hot tests of steel 56 

Hussey, Howe & Co 43 

Huston, Charles, oa steel 33 

Hydraulic riveting 100, 117 

Impure iron 433 

Impurities in castings 10 

Impurities in steel 37 

Incrustation and corrosion 422 

Indirect transfer of heat 195 

Ingot iron 27 

Injector, GifFard's 352 

Injector, Seller's 352 

Injector, Schutte & Goehring's 365 

Injury by cold feed water 370 

Inspirator, Hancock's 361 

Inspecting plates 73 

Internal corrosion 432 

Internally fired boilers 257 

Internal heating surface 191 

Iron, corrosion of 433 

Iron CJad Manufacturing Co 384 

Iron, elastic limit of 150 

Iron from Rodger's bed ore 57 

Iron modified by working 18 

Iron plate, analysis of 16 

Iron, transmission of heat through 196 

Iron, treacherous at low heats 144 

Iron, tensile tests for rivets 115 

Isherwood, B. F 146 

Jarvis' furnace 317 

Jarvis, K. M 317 

Johns, H. W 389 

Johnson, R. W 147 

J oints f or large flues 259 

Joints, riveted 86 

Joints under stress 102 

Kelley's sectional boiler 443 

Kelley, Wm. E 443 

Kemp's boiler cleaner 426 

Kennedy's spiral punch 92 

Kent, R 41 

Kirkaldy, D., on properties of iron 18 

Kirkaldy on testing iron 84 

Knowles, L. J 348 

Knowles Steam Pump Works 272 

Krupp's iron.,... 35 



PAGE 

Kunkle's safety valve 403 

Lap joints, riveted 121, 124 

Lap welded joints 136 

Lancashire boiler 260 

Lancashire boiler, H. P. of 211 

Landore-Siemens steel 35 

Lane's pressure gauge 407 

Large fire boxes 279 

Law in regard to boiler plates 74 

Leaky joints 431 

Leaky tubes 179 

Leaking through rivet holes 371 

Length of specimens 72 

Lifting pumps 388 

Lignite, combustion of 318 

Lime, carbonate of 422 

Lime extractor, Stilwell's 376 

Lime, sulphate of 422 

Limit of elasticity 79 

Limit to tensile strength 63, 70 

Liquids, conduction of heat by 190 

Lloyd's Register 39, 70, 73 

Lloyd's, Foster, best iron. 69 

Lloyd, Son & Co 23 

Locomotive boilers 298 

Loss of heat by scale 425 

Long and short specimens 58 

Loss by punching 89 

Lower grade of iron for boilers 67 

Lowmoor iron 69 

Low temperature, effects on iron 144 

Low T. S. of steel 61 

Lugs for boilers 308 

Lunkenheimer's safety valve 403 

Machine flanging 139 

Mahogany for scale 428 

Malleability 20 

Manganese in iron 4 

Manganese in steel 46, 53 

Man holes 184 

Martell, Mr 70 

Metals, conducting power of 189 

Mild steel 27 

Mississippi gauge cock 418 

Molasses for scale 428 

Molecular changes in iron 140 

Montgomery, J. F 309 

Moore, George W 372 

Moore & Kerrick 340 

Moore's boiler feeder 372 

Mud drums 306 

Mud, removing from feed 378 

Napier, James R 196 

Nashua Iron and Steel Co 55 

Newark-Cornish boiler 261 

New Jersey Zinc Co 45 



INDEX. 



453 



PAGE 

New York Safety Steam Power Co 282 

Nicks in samples 72 

NilesTool Works 280 

Non-adjustable injector 356 

Northcote, Henry 208 

North-of-England iron 69 

Nozzles for boilers 183 

Nuts, cold punched , 90 

Nut galls for scale 428 

Open hearth steel 52 

Otis Iron and Steel Co 58 

Overestimating tube efficiency 276 

Overheating steel plates., 142 

Overstamped plates vs. law 74 

Oxidation in welding 134 

Oxygen, free 136 

Oxygen must be kept from steel 119 

Park, Brother & Co 39 

Patching ; 9 

Peat, combustion of 318 

Peclet's experiments on heat 196 

Pennsylvania R. R. boilers 298 

Percussion tests 81 

Petroleum for scale 429 

Phillips, Nimick & Co 23 

Phosphorus in iron 145 

Phosphorus in steel 37 

Phosphorus not removed by the Besse- 
mer process 46 

Pierce, Henry M 333 

Pierce's furnace 334 

Pig iron 7 

Pipes, passage of air through 315 

Pitting 434 

Planing edges of plates 126 

plates for boilers 143 

Plates injured by calking 127 

Plates overstamped vs. law 74 

Plates to be stamped by law 73 

Plates, welding of 131 

Pook, Samuel H 55 

Portable boilers 295 

Position of heating surface .'.. 192 

Post & Co 410 

Potash for scale 429 

Potatoes for scale 428 

Power pumps 338 

Pressure gauges 405 

Pressure gauge, Bourdon's 406 

Pressure gauge, Edson's recording 413 

Pressure gauge, Holt's 409 

Pressure gauge. Lane's 407 

Pressure gauge. Post & Co 410 

Pressure on boiler heads 155 

Pressure on rivet heads 118 

Prevention of scale 426 



PAGE 

Priming 282 

Properties of iron, modified 18 

Properties of steam 205 

Proportions for riveted joints.. 122 

Proportions for stay bolts 175 

Proportions for steam drums 183 

Proportions for vertical boilers 277 

Prosser's tube expander 177 

Puddling 19 

Pumps 337 

Pumps, auxiliary 3.')0 

Pumps, capacity of 337 

Pumps for deep wells 346 

Pumps, power 338 

Pumps, steam 340 

Punch, action of on plates 109 

Punch and dies 90 

Punch, Kennedy's spiral 92 

Punched and drilled holes 87, 1('5 

Punched holes, conical 89 

Punching and annealing 48 

Punching, bad effects of 86 

Punching brittle iron 92 

Punching, experiments on 93 

Punching good iron 90 

Punching, loss of strength in 89 

Punching steel plates 47 

Punching thick plates 106 

Quality of boiler plate 15 

Qualities required by law 7* 

Radiant heat 187 

Radiant heat from wood 189 

Radiation 186, 188 

Ramsbottom's welding machine 138 

Rate of evaporation 204 

Rating boilers by heating surface 278 

Raritan Woolen Mills 439 

Reaming out punched holes 87 

Recording gauge, Edson's 413 

Records of U. S. tests, how kept 76 

Red short iron 17 

Reduction of area in tests 77 

Refuse fuel 313 

Reheating and cooling 141 

Removal of scale '. 426 

Requirements of iron 83 

Requirements of a steam pump 340 

Resistance to collapse 171 

Resistance to conduction 196 

Resistance to shearing 56 

Return steam trap 369 

Richards, C. B 58 

Richardson's safety valve 398 

Rings for man holes 184 

Rivet heads, pressure on 118 

Rivet-iron tests 115 



454 



INDEX. 



PAGE 

Riveted joints 86 

Riveted joints, friction al resistance in.. 119 

Riveted joints, strength of 98 

Riveted joints, ultimate strength of 15') 

Riveted shells, strength of 148 

Rivets, spacing of 123 

Rivets, steel — faults of 119 

Rivets, testing 113 

Rivets of steel 56 

Riveting, double 124 

Riveting, single... 121 

Riveting, influence of pressure on 118 

Riveting in flues 233 

Rocking grates, recommended 330 

Rodger's bed ore, analysis of iron 57 

Rogers, Joseph G 430 

Root's boiler 441 

Rough iron not the strongest 85 

Rubber gaskets 432 

Rusting of boilers 431 

Ryder's grate bar 309 

Safe load on stay bolts 173 

Safety, factor of 149 

Safety and stop valve 397 

Safety apparatus 393 

Safety plugs... 420 

Safety valve 393 

Safety valve and dangerous connections.. 395 

Safety valve and grate area 394 

Safety valve, Ashcroft's 399 

Safety valve, Crosby's 400 

Safety valve, diameters of 394 

Safety valve, Kunkle's 403 

Safety valve, Lunkenheimer's 403 

Safety valve, Richardson's 398 

Safety valve, how connected 394 

Safety valves, table of 404 

Salt in feed water 423 

Samples, nicks in 72 

Samples, size and shape of 71 

Samples, for elongation tests 76 

Sand, removing from feed water 378 

Scale and location of tubes 241 

Scale, chemical agents for 428 

Scale, formation of 423 

Scale in boilers 373 

Scale, injury to boilers by 423 

Scale, loss of heat by 425 

Scale, preventives to be used 431 

Scale, prevention and removal 426 

Scarfing and welding.... 134 

Scarf-welded joints... 136 

Schutte& Goehring 313 

Schutte & Goehring injector 365 

Scrap steel 56 

Seams not to be chipped ,. 126 



PAGE 

Sectional boilers 437 

Sellers, William & Co 352 

Semi-portable boilers 297 

Setting boilers 304 

Setting cylinder boilers 220 

Setting grate bars 307 

Setting internally fired boilers 258 

Shapley's boiler 272 

Shearing and tensile strains 11* 

Shearing rivets in joints 122 

Shearing steel rivets 56 

Shearing tests of stay bolts 113 

Shearing tests of steel 60 

Shells for boilers, thickness of 242 

Shell iron 22 

Shock, W. H 113 

Short and long specimens 59 

Siemens-Martin steel 52 

Siemens-Martin steel, limit to T. S 68 

Silica in water 423 

Silicon in Bessemer pig 44 

Silicon in iron ^ 4 

Silicon in steel. 37 

Singer, Nimick & Co 62 

Single riveted joints, calking 129 

Single riveted joints, strength of 66, 98 

Single riveted lap joints 121 

Single riveting, table of 124 

Six inch flue boilers 232 

Size and shape of samples 71 

Sligo Iron 25, 77 

Slusser & Suiter 290 

Small fire boxes 279 

Smith, Vaile& Co 341 

Snowden, Thomas, feed pipe 371 

Snyder's vertical boiler 283 

Snyder, Ward B 284 

Societe Alsacienne, etc 266 

Soldiers' Home, Ohio, tests at 236 

Solid drawn tubes 172 

South Metropolitan Gas Works, tests at.. 263 

Space between tubes 240 

Spacing rivets 123 

Specimens, length of 72 

Spiegel-eisen 44 

Spiral and flat punching 93 

Staffordshire iron 69 

Stamping boiler plates 73 

Stay bolts 172, 270 

Stay bolt tests 113 

Stay bolts with nuts 174 

Staying boiler heads 176 

Staying flat surfaces 175 

Stay rods 176 

Steads' circulating generator 384. 

Steam Boiler Applianoe Co 367 



INDEX. 



455 



PAGE 

Steam drum 183 

Steam domes 180 

Steam, dry 241 

Steam generators and economizers 387 

Steam jets for lifting wating 340 

Steam jet blowers, sizes of 314 

Steam jet for draft 312 

Steam pipes, covering for 392 

Steam, properties of 205 

Steam pumps 340 

Steam room 183 

Steam room, feeding water into 372 

Steam riveting, tests of 117 

Steam trap, return 369 

Steel, advantages of for boilers 30 

Steel bars, strength of 56 

Steel boiler plate, carbon in 30 

Steel, definition of 29 

Steel for boilers 29 

Steel, incipient fractures in 33 

Steel injured by punching 108 

Steel, nature of must be studied 31 

Steel not injured by drilling 108 

SI eel plates, annealing 143 

Steel plates, defects in 32 

Steel plates, ductility of 33 

Steel plates, experiments on thick 106 

Steel plates, faults of 36 

Steel plates, limit to T. S 68 

Steel plates, punching 47 

Steel plates, strength of 68 

Steel plates, stretch of 72 

Steel plates, welding of 137 

Steel plates, why a failure 32 

Steel rivets, HG, 119 

Steel rivets, burning of 119 

Steel rivet tests 116 

Steel, scrap 56 

Steel, shearing tests 60 

Steel, tensile strength of 38 

Steel, texture of 29 

Steel, treacherous at low heats 144 

Strength of American plate 69 

Strength of boilers 148 

Strength of butt joints 103 

Strength of riveted joints 95 

Strength of plates in flanging 140 

Stilwell & Bierce 376 

Stilwell's lime extractor 376 

Stone for boiler foundations 308 

Stop and safety valve 397 

Stoy, C. S 432 

Strainers 339 

Strains in boilers 371 

Strains in cooling 9 

Strength of punched and drilled holes..., 91 | 



PAGE 

Strength of riveted sheUs 148, 153 

Strength of stay bolts ;.... 173 

Strength of steel plates 106 

Strength of welded joints 133 

Strengthening flues 171 

Stretch of homogeneous plates 72 

Stretching Iron 77 

Sturtevant, B. F 314 

Sulphate of lime 424 

Suiter's boiler 290 

Tangye Brother & Holman 263 

Tanks for water reserve 338 

Taonate of soda for scale 430 

Tannic acid for scale 428 

Tearing and breaking samples 72 

Tenacity and ductility 18, 34, 78 

Tensile and shearing strains 114 

Tensile strength of boiler iron 23 

Tensile strength, limit to 17 

Tensile strength of steel .38 

Tensile strength of Bessemer steel 51 

Tensile strength of crucible steel 42 

Tensile strength of open hearth steel 01 

Tensile strength of rivets, steel 120 

Tensile strength, specimensfor 07 

Test, bending 66 

Test, bulging..; 81 

Test, drifting 67 

Test, forge 83 

Test, percussion 81 

Test, temper 66 

Tests, how U. S. to be made 73 

Tests, how U. S. records to be kept 76 

Tests of iron, Kirkaldy's conclusions 84 

Testing steel plates 40, 161 

Tests of rivet iron 11,3-5 

Temperature, effect of low on iron 144-6 

Temperature, escaping gases 387 

Texture of flange iron 27 

Texture of steel 29 

Texture of wrought iron 19 

Thickness of flues 171 

Thickness of plates for boilers 165 

Thick steel plates 106 

Thin fires must not be used 119 

Thornycroft best best iron 69 

Thurston, R. H., on H. P. of boilers 212 

Three inch tubular boilers 243 

Three and a half inch tubular boilers.... 250 

Tidal circulation 216 

Tightness of joints 165 

Torsional tests of rivet steel 120 

Torsional tests of steel for boilers 50 

Toughness in boilerplates 18 

Toughness in plates, U. S. law 74 

Transfer of heat 186 



456 



INDEX. 



PAGE 

Transmission of heat 196 

Transmission of radiant heat 189 

Trevithick, Richard 258 

Tube areas, table of 248 

Tube and grate areas 239, 249 

Tube area in vertical boilers 278 

Tube expander 177 

Tubes and circulation 238 

Tubes as braces 177 

Tubes as heating surface 192 

Tubes, cutting to length in place 178 

Tabes, defects in large 132 

Tubes, distance between 241 

Tubes for vertical boilers 276 

Tubes, Galloway's 268 

Tubes, height'of 240 

Tubes injured by firing 279 

Tubes, interfering with circulation 214 

Tubes, length of 239 

Tubes, location of 241 

Tubes, number in. a boiler 239 

Tubes, space between 240 

Tubes, strength of 172 

Tubes, tool for calking 179 

Tubes, wasting of 279 

Tubular boilers 238 

Tubular boilers, 3 inch 243 

Tubular boilers, 3>^ inch 25i) 

Tubular boilers, 4 inch 252 

Tubular boilers, 6 inch 234 

Tubular boilers, compound 254 

Tubular boiler, test of 253 

Tubular boilers, length of 239, 245 

Tubular boilers, proportions 238 

Tubular boiler setting 305 

Tubular boilers, vertical 276 

Turned iron, not weakened 85 

Two-flue boilers 227 

Ultimate strength of boilers 148 

Ultimate strength of riveted joints 150 

U. S. tests, how made 75 

U. S. Treasury, tests of iron 68 

Value of tube surface 193, 278 

Varieties of plate iron 22 

Vertical boilers 269 



PAGE 

Vertical boilers, fire boxes for 272 

Vertical cylinder boilers 222 

Vertical flue boiler 270 

Vertical tubular boiler 275 

Vertical tubular boiler, faults of 282 

Vertical tubular boiler, proportions 277 

Vibrations of a plate 140 

Victor heater 383 

Vinegar for scale ». 428 

Water bottoms 296 

Water charger 350 

Water, feeding into steam room 372 

Water gauges 419 

Water, hard or soft 422 

Water not a good conductor 213 

Water, required for boilers 337 

Water, required per H. P 210 

Watts' rule for H. P 211 

Water space, vertical boilers 272 

Weakening of shell by domes 180 

Webb, F. W., on Bessemer steel 48 

Webb, F. W., on punching 94 

Welded boilers 136 

Welded joints, strength of 133 

Welding blooms 20 

Welding boilers 131, 136 

Welding, oxidation in 134 

Welding prevented by cinder 134 

Welding, scarf 135 

Welding steel plate^.;.. 137 

Weldless rings for Wl6rs 138 

White iron I 6, 16 

Williams, C. Wye...} 193 

Wilson, Kobert f 215 

Workington iron, analysis of 57 

Wrought iron, classification of 19 

Wrought iron, elastic limit 80 

Wrought iron for qoilers 15, 67 

Wrought iron, proi)erties required 16 

Wrought iron, texiture of 19 

Yorkshire iron....j 35, 69 

Yorkshire and Essen plates 78 

Zigzag and chain jriveting 109 

Zinc for scale ; 430 



</^N 589 



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